Whether they should truly be missed or not I'm not entirely sure. I certainly do prefer to have them in - they are quite useful at times, and other times just plain fun. I tried to find cheat codes for Heroes 6 because, fuck you Ubisoft and/or Black Hole Entertainment (whoever is responsible) the "balance" in the campaign is complete bullshit. However, there were no cheat codes. I ended up just going for a trainer instead which is a viable alternative to cheat codes. Some times I even whip out Cheat Engine myself and start to much around with a game.
Another good use that comes to mind were the console commands that Half-Life taught me a lot about games in general, and I'm eternally grateful for that (well, I know, even if Quake did it before, as HL was running on the same engine).
Some of the cheat codes even took a life of their own - the Konami code, being one example, but also the likes of the cow level, or "power overwhelming" in Blizzard games.
Overall, though, they were a nice addition, but not entirely necessary - nowadays trainers and other applications can do a pretty serviceable job substituting for them. Again - wether they should truly be missed, is a bit muddy.
A wide selection of gaming magazines
I should start off with saying that I certainly didn't have a great selection of gaming magazines. And the ones I had access to, were a bit shit. Still, given that I had no internet access at the time, they were passable.
However, I don't think I'll really miss them, even if a wider selection were to be available. Due to the ready availability of the Internet nowadays. I can go and find several places to suit my tastes - from general gaming websites such as this one, to some that cater to more specific tastes, say, a given console or a particular genre of games, to some even more targeted like a given game, even down to a specific entry in the series or even a particular aspect of the game. And, frankly, I much prefer those - there is more freedom, they would cater even better to me, and chances are, they'd be less bad than the paper magazines I had to grow up with.
Overall, I don't think magazines are a big loss. Whether it is one, to begin with, would be up for debate as well.
I'm splitting this point into two. So, demo discs. Yeah, fuck those. I've got the power of the Internet now - I've had it for quite a while now. Discs, I can totally get to skip - the disks included with magazines, in particular, were filled with a bunch of crap that, again, filled the Internet shaped hole in many people's lives. They even distributed stuff like free (usually shareware) games, software, and patches for the games. And fuck that patches nonsense - I see people claim it's some sort of a new phenomena to have a game released and then the developers somehow dare release a patch you had to download, perhaps on day one...well, how about you get a game and there is no patch until maybe you go buy the next edition of a gaming magazine in a fortnight. If they bothered to include that patch with it. And in the mean time, the game could literally be unplayable or unwinnable or maybe just unprogressable in some fashion.
Nah, as I said, I've got the Internet now - games, demos, software, patches, mods, whatever - I've got ready access to them. Much bigger, much better selection and I can get them pretty much instantly.
(and demos in general)
OK, demos we certainly don't see as many of these nowadays. And that is a shame - sure stuff like let's plays or an overwhelming amount of reviews exist, but they don't quite manage to convey as much and the same kind of information as a demo can. In fact, I'll bring up Heroes 6 again - I know it may sound a bit odd, but would not have gotten it were it not for the demo. Thanks to it, I managed to see what the game is about which the few reviews I had seen at the time, didn't manage to properly convey.
I do think demos are benefitial to us, the players. I realise they may not necessarily be for the publishers and/or developers but I'm not entirely sure that the we should be serving their needs when they are marketing stuff to us. I don't market stuff works.
Game hint hotlines
Frankly, I never heard of these until now. I don't think they would really "enrich" us either. Probably gets boring but - the Internet. If you're here, you have access to much more, much wider, much better advice for much cheaper. Namely, at the price of free.
Decent instruction manuals
Yeah, I still remember the ones which were actually wrong. Spells of Gold sticks in my mind as a sore thumb - I never managed to find out how to learn spells. I knew spellcasting was in the game (even if the title didn't pretty much explicitly say it), the manual did, in fact, spent a good chapter on spellcasting, but I managed to finish it without ever finding out how do do any of that. I remember reading the manual several times each time growing increasingly more puzzled as to what was it I was missing. It was only after I finished it I managed to find out you had to press Tab while in a temple, to be able to buy spells. Incidentally, I found that in a review on a gaming magazine that complained about this information completely missing. Yeah, that was one "decent" manual, that was. There were others that were wrong, too. I remember some were even outdated - if memory serves, Neverwinter Night was one of these. The descriptions were correct as of the time the game was released but later patches/expansions and accompanying changes to the mechanics made the manual quite inaccurate at places. And some manuals took the worse of both aspects - they were intended to be accurate (as of the relase of the game, at least) but they...weren't - they would reference mechanics that have been changed and tweaked before release. So, they were outdated at the release of the game...which can be equally be interpreted as the manuals being plain wrong not merely being correct at one point in time, because as players, we never experienced that point in time.
Some lore stuff from them was OK to good, some was bad to cringeworthy, though. The manuals were quite a mixed bag - I certainly don't remember them being some sort of always must-to-have and really-high-quality reading. I do think they can be good, but the sheer demand to have them with almost every game, made a sizeable portion of them just a half-assed attempt in order to tick some box in the "To Do List For Releasing".
I say that if a developer wants to make a manual, they should, they would be likely to put some effort into it. If they don't, then they probably shouldn't bother. And if they want to relay the same information in a different way, they are totally free to do that. Might even be encouraged, instead of adhering to a "standard" that may not always be the best for relaying useful information.
A distinct lack of hand-holding
Yeah, I certainly miss that at a somewhat regular basis. The games that insist on educating me on absolute basics do frustrate me - game starts and I am taught that I can look around *gasp* SUCH REVELATION! And I can walk, MUCH SURPRISE!
Yeah, I know the game could be the first one for some, but come on, let's look at this realistically - it wouldn't be for most players. The tutorials should be optional - be they a separate thing you can play, like the Hazard Course in Half-Life, or a togglable option (it's fine to have tutorials on by default). An even better approach is to offer the choice whether to have them in the beginning of the game - Bloodlines was quite brilliant where you were given a choice between playing the tutorial level, which taught you how to move, attack, jump and stuff, covering most of the basics for playing a game in general; being given the basics, which was a brief verbal run down of how stuff works in this game (in-universe-wise) and hence what to do/not do; or completely skipping either of these. Other games have gone with a more boring but practical option that is to when they just go "Here is a tutorial hint - if you don't want to get these, click <whatever>" when the game starts.
So, what I'm trying to say is - yes, tutorials are valuable. But they can also be frustrating for a large portion of the playerbase, as well. And we have the technology, methods, and precedents to have a compromise.
Big graphics jumps
I'm not sure how I feel about this. I mean - yeah big graphics jumps were cool and all but...should we really miss them? Come one, is that really a thing we need? I don't mean better graphics - overall they are a good thing but what I mean is big sudden and infrequent jumps in them. I think that a steady pace is much better - sure you lose some of the "wow" factor when things are suddenly upgraded, but surely, having things looking better all the time should offset that, right?
I don't really think this is something to really miss.
Meh, whatever. They were OK but also not really that awesome. Sure, I've spent quite a few hours in arcades. Some of these hours I've even played on them. But so what? I've also spent quite a few hours catching spiders and pitting them against each other in fights to the death. And I've also spent quite a few hours doing other stuff that amused me when I was a kid, but not as much nowadays. I was easily amused as a child. I'm pretty sure most youngsters are.
Anyway, back to arcades - they are gone, and with somewhat of a good reason - they aren't really that good. Well, not compared to the alternatives for gaming that surpassed them. After all, they wouldn't have been surpassed, were that not the case. Should we really miss something that just became obsolete? Living in caves and risking your life for food was all the rage back in the day, but I don't really think we miss that by and large. At a different point in time, attaching leeches to the body was a medicine practice that was...well, used. Do we yearn to go back to it? OK, maybe these examples are slightly on the negative side, but some stuff was simply replaced with better things - cassettes were replaced with CDs and later MP3s, for a more practical example. Sure, one could remember fondly the times they had to rewind the tape, sometimes by hand, but there isn't a really big rush on buying cassette players, which suggests they aren't really that missed.
Arcades had their time, but it passed. Eh, whatever - another note in the history books. Yearning for them strikes me as being bit of overly romantic.