This sort of makes sense for sports games. Updated official rosters, changes in strengths of each team, and ways to make the game feel more realistic are reasons why we all generally feel that they deserve to have annual releases. It makes sense.
However, it really doesn't make sense from any standpoint aside from a simple cash-grab by the publisher to release other genres annually. No, Activision, we really don't need yet another Call of Duty this year or another Assassin's Creed, Ubisoft.
Instead of focusing on quantity, why not instead focus on quality? It's something both of those game franchises deserve more of.