Every time I watch the Godfather I or II, or some other great movies, I wonder why they can't make more great movies.
My conclusion that it is the fault of audiences. If Hollywood can just make crap and it sells, then why bother making something great.
The more people pay to see moronic movies like Batman (The Heath Ledger one was good but the others are crap), Avengers and all of that crap, the less likely Hollywood is to make more great movies.
TV has similar issues. The regular networks can't have anything great anymore because they have to appeal to the masses, most of which like crap. Luckily, the cable channels are putting out some good shows because they can have a narrow target audience.
The recent Pacino movie was decent (Danny Collins). Not great or anything, but much better than some Avengers crap.