Well I've had this problem with a few. Original Super Smash Bros did not age well in my opinion. Plays very slow compared to Melee and Brawl and just with a lack of options the other 2 has, it is hard to go back and play it.
Also a lot of 2005/2006 360 titles did not age well at all. Gears 1, Dead Rising, Call of Duty 2, Lost Planet, and GR: AW to name a few. Give or take, all 3 I wasn't too impressed with anyways, all of them have had more competent sequels or similar games released after them that really make them obsolete to me.
I'd say all the early RE games really aged terribly. They weren't really amazing to begin with, but when you start getting into modern controls and modern camera controls they come off as somewhat of a B title nowadays. Although the remake on the GC really helped it out, it is really hard to go back and play them without the advances we have had in the 3rd person action genre.
That's about all off the top of my head I can think of. I mean some games age better than others usually based on simplicity. I mean things like the Mario games are so simple that they really don't show age because of it. While the games of old that try to be graphical powerhouses or make "innovations" then don't seem to age well because it is always been improved on. But no need to improve on Mario because it is fine the way it is. Then there are somethings like Ocarina of Time or even the first Halo game where it is done so well then and so far ahead of its time, that we are still waiting for everyone else to catch up.