Yeah, I also find that kind of annoying.
Mind you, I don't care about achievements really at all. Never have, and they never will be a priority to me.
But I kinda feel like... "Man, if they are gonna HAVE achievements, they should be for better things that have to do with MY single player experience and not so many online things that I know i'm never going to even feel the least bit compelled to try for."
See.. my favorite achievements, and the way I believe they should work is that you just get achievements randomly for doing a certain thing during the course of the game, not have to try and go out of your way to reach them.
The only satisfaction one ever gets from them anyway, is just seeing a little thing pop up on the screen. So, it should be more for things like "do every grapple move" or "play every character", and things like that. Things that just happen when you get to them and you're like "Oh cool did I play as everyone already?"
You know what I mean? The best achievements are the ones you don't know that you achieved, until you did them.