DLC. Its optional, for one, and to me, I love that games actually have support after release now, instead of the days of the N64 where what you got is it, no chance to fix bugs or anything.
On a similar note, Call of Duty and Madden. I don't get why people have such a huge hate for it. Sure, its yearly, and doesn't have humongous changes per game. But the reason people buy those games isn't for that. Its for fun, for hanging out with friends, playing with the latest rosters or new maps. Its mindless fun, that's all. Not every game out there needs to be a award winning masterpiece of a story.