Most of the games I emulate are game's I've owned hard copies of. I've owned an NES, SNES, Genesis, GameBoy, N64, PSX and on up. Maybe it's because I've played the games on their original hardware by in some cases thr emulation can be better. No more having to worry about glitchy cartridges or controllers tha stop working. Plus having it all on one device instead of being spread across several different consoles (that all take up space around your tv.)
I dunno, I'm pretty partial to emulation even if just to conserve space. Plus like Ratty said, we have te entire history of gaming available online for free. I can't see how that's a bad thing. I like that if I'm somewhere and want to play CV1 I can just download an emu and a rom quick and get my fix.