Well, for the most part I just consider them the challenges of the games, mostly to be taken or left. I rarely get all the points in a game (currently only 8 out of over 50 games.... and I barely count Avatar, The Burning Earth since I rented the game to see if it really is as easy as so many say it is... and now I think it's kind of joke to have it but I can't send them back.)
Also it can make for interesting challenges you can make for yourself, as for right now I'm on a mission to have an average of over 50% of my overall possible gamerscore before I put another game into it. This is tricky as for starters I rarely play online games so with many games I can't even try for many of the points, then there's the games that will add achievements that can only be gotten if you buy the DL content that I don't want (like Halo 3's 1750 possible points and I think at best I can get 1250) I'm still 1500 points from completing this and find it's been a great way to get me back to games I haven't played in a while and making up for my total lack of skill on Guitar Hero/Rock Band is a bit of a pain.
As much as I don't go about talking about it much, hell, this is the first time I've talked about the subject online. In the end, take it as you wish, just those that take it seriously, remember, you might be the only one.