Like it or not, big budget blockbusters make money and sell formats. Bluray has lots of them and more coming out. HD seems to pump out alot of low budget cult movies which don't have much of an appeal to the general audience. Don't get me wrong, I loved "Endless sunshine of the spotless mind", but not a movie to sell a format and neither is "40year virgin" or "Brokeback".
I have both spotless and 40yearold virgin in SD dvd, would I upgrade them to HD??? probably not, its really not the kinda movies to showcase HD.