what you call a quality game isn't what everyone else would call a quality game.
Quality isn' relative. You're talking about different game genres. MW2 is a great action game, and an absolute star in its genre.
I can imagine basing the pricetag around the length of a game though, but that concept is still very abstract since one person could spend hundreds of hours with a game before they consider themselves being done while another could be satisfied with 20-30 hours.
And you'd imagine people forking out more money to see a 3 hour long film instead of a 1,5h one?
Depends on the content, I guess. MW2 is short, but has a lot going on. There's literally masses of content, and the levels are masterfuly done.
The new Wolfenstein, however... still an FPS, some interesting ideas, but fell flat on its face.