Also a reason as to why they remake ps2 games for the PS3 (Or even the 360) is because they would not play on those consoles if they were in PS2 disk form. So they have to spend money to do that pretty much, meaning they lose money. But perhaps it's because they have so much money, they couldn't really care how they did this whole thing. For instance, if I had billions, I wouldn't care how I redesigned something. As long as I made the thing decent in the first place, it wouldn't matter how I spent my money redesigning it. They probably just can't be bothered to do this, even though they lose money.
All great gaming consoles are at war with one another. So it's not like they will make it so you can play every game on each console. Hence why they have exclusives. PS3 have games you CAN'T ever play on 360, and 360 have games you CAN'T ever play on PS3. Just how it is.
I say there would be no need to waste money remaking the already existing titles. They will waste their time on satisfying us all with future releases, if they bothered with this.