Yeah, I'm one of them. I don't play multiplayer games so that issue is meaningless to me.
And to each their own but I couldn't give less of a shit about SR3's story. GTA 4's characters are lifeless, boring, and easily the worst in the series history. SR3 isn't trying to be serious at all, so to complain about the story...they couldn't care less because they never tried to make some serious story. They wanted gamers to have fun, and that's why I play video games.
If SR3 being over the top and childish bothered you that much, then I don't know what to say. We're just not into the same kind of games I guess so there's no point in discussing it further.
Maybe this game is more up your alley:
https://www.youtube.com/watch?v=RWFJOxG5sSw