Lost in Translation has made 26 million to date. Mystic River has made 37. Those figures are far from shabby and they did have a fair amount of advertising each. These are popular films.
Hollywood is interested in making money, and they do a damn good jobm they aren't stupid. If they could make Titanic figures from a 10 million dollar "art film" instead of a 200 million block buster that could sink them if it flops, don't you think thats what they would be doing?
What do you expect them to do? put out an ad in variety telling people they have to see the new Altman movie or they won't be getting any super heroes next summer?

You can lead a horse to water...

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