Only one reason? How about longevity? My original GameBoy, Sega Genesis, and N64 (and every other console I've ever owned) all still work perfectly. If I want to play Sonic the Hedgehog, I can set up my Genesis in about 5 minutes and pop that sucker in the cartridge slot and go nuts.
Not only do my PCs tend to get really sucky after about 5 years, modern PCs seem to have some kind of issue with running really old PC games. It's much more of a headache to set up an old PC and monitor (if, for some reason, I kept my old Windows 98 setup) than to dig out my old consoles and plug them into the tv. It may be possible to run those old games on my newer rigs, but it's too inconvenient to bother with, especially not knowing whether I'll be able to pull it off. One example: I haven't been able to get Roller Coaster Tycoon to work since upgrading to XP a looooong time ago. And don't get me started about trying to game on a Mac -- I think the issues there are well-documented enough, yes?
I do play games on my PC, and I don't mind it. There are plenty of great PC games to be played, and Steam is an excellent service. But I consider it a supplement to my consoles, not a replacement.
