i don't see any problem with emulation, it works in the same way as people pirating music going out to buy it if they really like it. there is a huge vintage games market now, and as much as i like being able to play any opld game i want at any time in any way with any controller is pretty cool, but i will always ALWAYS prefer the feel to a console than playing an old game on my computer. this was made a little better when i was able to hack emulators into my wii, but it still aint the same.
i have the entire library of NES, SNES, Genesis, Atari, and some N64 (even though i have most of them on physical copy) but i think it would be so much cooler to have it all physically, especially for bragging rights. i personally plan on starting a small old games collection when the Retron 5 console drops, because it still runs off emulation but requires you to have the physical ROM cartridge. so i can play an old cartridge game on my HDTV with no hassle.
again, it works the same with all piracy. if you download it and you really like it, you'll go out and buy it. besides, many of these ROM cartridges aren't in production anymore and therefor are not being sold new. so the content producers recieve little to squat of whatever is made from used retro game sales. the only people you're hurting by downloading emulators is your local retro games concern which, chances are, will do just fine.