If the 3DS had a built in emulator for all previous nintendo systems, I would have bought it by now. I would be willing to pay a dollar or two for games. more than that, and its not worth paying for a game I've likely played before and just want to play for the sake of nostalgia.
Or Sony's NGP, if it comes with ps1, ps2 and psp emulators, I won't even think twice about getting it. However, if they charge 15ish per game like it seems they want to do with the games for xperia play, it'll be DOA. I don't see anyone paying more than a couple dollars for 10 year old games they've already played.
I was peeved when I found out my newly purchased PS3 wouldn't play my ps2 games. Is it really that hard for them to develop an emulator for ps3 so it can play my extensive collection of ps2 games?
I'm one of those people that don't mind paying to get something legitimately, but when nintendo/sony/etc don't even offer these things, I'm left looking to the community to provide such things. So, with emulators pulled, we'd better see official releases.