In related news, I always wonder why Sony doesn't do the same with their PSN games. I think they could sell quite a few collections this way. Especially now with PSN being compromised, a lot less people are going to want to buy through the PSN store.
They could make the following and it would sell well:
PixelJunk collection (racers, eden, monsters, and shooter)
"Stunt collection" (Joe Danger, Pain, and something else)
Zombie collection (Dead Nation, Burn Zombie Burn, Age of Zombies, etc..)
Anyway, it's too bad Sony will likely never do this