Well first of all you must be referring to a commercial product, definitely not a free one, since Sony is very commercial.
Now, selling an emulator is a very delicate matter.
first it is quite impossible to guarantee 100% compatibility (I think someone said even PS2 can't play all PS1 games).
So Connectix (VGS) and bleem had to make a big disclaimer that not all games work, and advise customers to always check their compatibility lists before buying the emulator or the game.
but even so they had to have a HUGE testing department to keep testing games, as many as they can. and do it all over again whenever a new version comes out.
You can see it isn't very profitable. So bleem! for DC is really not a dumb move. They only have to support one game instead of hundreds, and sell it for about 1/10th of the price of bleem! PC. Not to mention the inherent difference between a console and a PC software product: one versus many varieties in system specs.
Now if you are Sony looking at all these facts, would you do it? I wouldn't.