I'm late to the conversation but want to add my 2-bits worth anyway... I agree with a lot that's been said in the thread so far. Nostalgia is certainly a part of it for me, especially with my favorite old-school systems - the Lynx and TurboGrafx - neither of which has a huge library to draw from (yes, I know the PC Engine has about one bazillion games available, but I only have US hardware). Besides that, I simply have a limited amount of time and money for games, and retro gaming offers the best bang for the buck. We own all the last-gen consoles (XBox, PS2, GameCube and Dreamcast x 2) in our house, and there are plenty of games for these systems I haven't got around to playing yet, despite the fact that I own them (God of War, Shadow of Colosus, Final Fantasy XII, Metal Gear Solid 3 Snake Eater, Killer 7, Resident Evil 4, Trigger Heart Excelsior, etc.) - I picked most of these games up cheap, used, because I know I'll like them and I know I want to play them, but I hardly get in any console game time in the summer, so they'll have to wait until September before I start looking at them... That's okay though, because with the exception of recently published DC shmups, I pretty much refuse to pay more than $20 for a game, and I usually get them for less than that (pawnshops mostly - drifting around the streets on my lunch hour).
I've played Gears of War and Advanced Warfighter and Guitar Hero II on a friend's XBox360, and they're certainly fun, but they're not any more fun than the stuff I have in front of me to play now, and they'll still be fun when I finally get around to playing them at $20 a pop on a $200 XBox360 three or four years from now... We have many friends who own a Wii, and playing Wario or Wii Sports is a kick when we visit them, but it doesn't feel like the kind of thing I'd spend lots of time doing at home, so what's the rush?

Of course, with our constantly-in-a-state-of-barely-controlled-chaos schedules (we've two teenagers in the house, after all) portable gaming makes the most sense, and everyone in the family has a DSLite, and these systems see a lot of use. There are also two PSPs in the household, and my GP2X is my retro portable, so the vast majority of our gaming is done on handhelds, which tend to have a decidedly retro feel in most games anyway. Maybe our tastes just gravitate to that kind of gaming (platformers, shmups, 2D fighters, classic JRPGs etc.)... Or maybe I'll just be damned before I drop $600 on a video game console
