I could have had a next generation system right now. But I chose to go with the retro stuff. Right before Christmas I bought a Neo Geo CD. I always wanted one. And now I have been buying the games. I have also been picking up games for my other retro systems. Just today I purchased "Test Drive Le Mans" for my Dreamcast. (Won it on ebay for .99 cents. Factory sealed) There are just a lot of games that for one reason or another I was not able to get when the systems were new. In the last six months I have purchased games for the Neo Geo CD, Gameboy Color, Swan Crystal, Dreamcast, Turbo Grafx 16, Sega Genesis, and N64. And also games for the Game Cube and PS2, but I would not exactly call that retro just yet.
I too would consider the only thing that I have, that is next gen, would be my DS.
It all depends where you want to go right now. (As some have already said, the old stuff will get harder to find and more expensive to buy.) Do you want to go back and catch some of that gaming goodness that you missed? Or do you want to get on board and enjoy what is happening right now?