My reason is
That the Amiga was all about innovation in gaming (As far as I'm concerned), Joe Bloggs of the street could program a world beating (Original) game that could outsell any Software House produced title (Worms for instance), but now the hardware has moved on so much it's almost impossible for the little man to compete with the big boys (ie The average cost of game development for PS2/GameCube/X-Box is rumoured to be in the millions).
The last game to bring something new to the table was Wolfenstein 3D IMO, since then we have been bludgend with countless clones, rip-offs, upgrades and revamps making gaming on a whole (For me) a major dissapointment.
So playing these games on emulators lets me remember the good times of gaming and makes me think that one day, the software giants will get their acts together and bring back the golden age of innovation.
Sadly I don't think it'll ever happen.