Sure I can watch my Blade Runner DVD on my PS3, but I prefer to watch it on blu-ray.
I think this is a good idea for the industry, and I own a 60GB launch PS3. It's not a new idea really (Resident Evil 2, 3, and CV ports to GameCube, etc). I think it's analogous to buying the same movie on VHS, LaserDisc, DVD, and then Blu-ray. If you like the movie enough to watch it repeatedly, you want it to look as good as it can. Same with games. I don't necessarily want total remakes of all my old favorite games; remastered visuals and audio would suffice for most. FF VII really could use a total remake. FF VIII and IX however would be just fine with higher res in game graphics, uncompressed FMV, shorter load times, and enhanced audio.
I have a hardware backwards compatible PS3 and still have my copies of GoW I and II (I still enjoy playing from time to time). So I don't NEED to buy this new set to play the games. However, if it's a true remastering, I'll consider upgrading to the PS3 collection because I love the games and would like to see them look as good as they can. Of course I'll wait for the inevitable comparisons of the blu-ray version with the original versions before I consider buying. It will have to offer a substantially better visual experience than playing my PS2 discs upscaled (and I couldn't care less about Trophies), otherwise I'm better off playing them on a PC via emulation.