This guy was a star. Just think Top Gun, Willow, The Doors, Tombstone, and Heat.
Why does he only do B-movies nowadays, and even small roles in them, at that?
It sounds like he could be pretty rude to people when he was at the peak of his success. He's said he just was trying to make the best movie possible, but I'm not sure how treating directors and other badly would. Also, he knew what was in the scripts of these movies when he signed on. He burned a lot of bridges, so when his career floundered, there weren't a lot of people who really wanted to help.
There's a documentary about the box office disaster Island of Lost Souls that's pretty interesting. Kilmer and Brando together. Dealing with two of the most difficult actors in the business, at least that was there reputation, and both of them felt like being difficult.