Theatre operators know that they can run a short film three or four times between 6:30 and midnight and a long film only twice. Something like 1900 they could run only once even in the final release, which was about 4½ hours. They know how many drinks and how much food they can sell, even at their horribly inflated prices, and they know that they make more with shorter films and no intermissions.
Businesses are quite good at evaluating their profits. Most movie theatres are owned by conglomerates, and they have legions of accountants figuring out how to make the most money. I imagine they know the ideal salt ration for making the popcorn and other prepared foods salty enough to maximize soft drink sales.
So the truly great long films are shown only at film festivals, where they can charge $20 or so for a ticket. Of course, these days the DVD is better, because the viewer can rewind it and stop it for food preparation and potty breaks.
Indian audiences, of course, expect long films and unless there is an intricate song and dance number or two in it to put in the teaser or on the posters, they might not attend at all. I am sure that DVDs and cheaper TVs have changed the market in India as well, but less so, because most Indians do not have air conditioning, and the town theatre is the only place where they might be able to sit in a cool place for any appreciable amount of time for an entire season.
I recall one theatre in Santo Domingo where the tickets were one or two pesos. For one peso, you sat in the part of the theatre that had no roof, and you were cooled by the sea breeze and fans. If it rained, you got wet. For two pesos, you got to sit under a roof, and there was more space between the rows of seats.