A game that tries to appeal to 100% of people will, at best, be a lowest-common-denominator mess, and very likely manage to turn off everyone because it includes something that they actively don't want in their game.
A game that targets a specific niche while not caring about others does not have that problem. Because the target audience is smaller, it can't support enormous budgets, but enormous budgets don't usually mean the difference between a good and bad game. And a game targeting a niche takes less money to develop, anyway.
I'm not certain if that's time/budget versus "simplifying the game for everyone".
It's easier to balance a game with 10 "sets" of armor + weapon - as opposed to having a myriad options of armor per body part and weapon combos/etc. DA:VG was the most beautiful but shallow Dragon Age game.