"For maximum damage, 280 Hit Rating, 24 Expertise, get Armor Penetration to 20% and then invest everything else in Strength," reads a typical post on websites like Elitist Jerks.
Players worship these guides. But it isn't a strategic decision; it's a math equation that someone else solved for us. Is a game strategic for making its systems so obtuse that you need to ask a gamer scientist for help? That's like saying that an adventure game is challenging because you have to try every item in your inventory to solve a puzzle. When I think of strategic RPGs, the first one that comes to mind is one of the simplest: Paper Mario.
A kindergartener could understand Paper Mario's system. Your hit points never went above the double digits. Damage was a straight Attack - Defense formula, with a bonus if you had good timing on the Action Command. Improving your stats by just a point was cause for celebration. Choosing between a +1 Attack badge and a +1 Defense badge was much harder, though. Both would profoundly change your gameplay, and you knew it. It reminded me of board games like Settlers of Catan and Puerto Rico; they give you simple relationships and then make you sweat over them.
There's one aspect of WoW where the results of player decisions are clear. Don't Stand in the Fire: a tense reminder for raiders to watch their feet as well as their health bars. If you see flames, you move out of them; it's simple, right? But it forces you to choose between casting a spell and avoiding damage. It's not the only complication in boss fights: fires, exploding players, adds (smaller enemies attacking along with the boss), breath weapons.
These simple concepts spur complex plans, debate, and experiments because the cause and effect are obvious. "Don't stand in the fire, don't be near anyone when the timer goes off, spread out in Phase 1, collapse to the right in Phase 2." If you stand in the fire, you die. If you're next to others when you blow up, they die. If Blizzard treated boss fight mechanics like they currently treat stats, then the fires would be invisible and only running complex mathematical formulas would allow you to know where the damage was originating. That would be a wonderful challenge! I can already hear the raiders screaming in joy!
Simplicity is visibility, and visibility means understanding. Understanding doesn't necessarily mean mastery, though. Just because something is made of simple components doesn't mean it does not allow you to think critically. You can write the complete rules for chess on a single sheet of paper. But critical thinking and strategy requires something more. It requires a variable.