it's mainly because it's the style of film that can't be made any more-
a massive blockbuster film with huge sets, but without CGI, with overtones of rascism and bizarre stunts, including an entire species of gorilla being violently made extinct with a giant ad-hoc laser rifle - by the main characters. It's preposterous in all the right ways, although by the end you're truly wondering what exactly the point was. I guess, don't like diamonds? Or mess with Susan Sarandan? Perhaps.