The advent of trophies and achievements has been one of the worst things in gaming for me because developers have less incentive to provide in-game rewards and think some stupid trophy or achievement is compensation enough when it's not (at least to me). Remember back when Vigilante gave you increased armor? I certainly do. But what did it give you in GTA IV? A stupid trophy and that's it. Same goes for cage fighting in TBoGT, which would have been a great way to reward the player with more damage resistance. But NOOOOOO, apparently I'm supposed to be happy with a worthless little colored icon with the words Bear Fight next to it. Maybe if I played games to impress other people with my exploits, I'd be happy with that stupid and useless little colored icon. But since I couldn't care less about what others think of my gaming habits, Sony can take those stupid and useless little colored icons and shove them.
So, basically, I'm hoping GTA V has in-game rewards for these activities in addition to said stupid and useless little colored icons.