Look at the Coen brothers. All their minor characters are as interesting as their protagonists. If the smaller characters are well-written, the whole world of the film becomes enriched. It's not the size of the thing, but the detail.
“Yes, women are stronger than us. They face more directly the problems that confront them, and for that reason they are much more spectacular to talk about. I don't know why I am more interested in women, because I don't go to any psychiatrists, and I don't want to know why.”
“What I object to the current government intervention in so-called 'solving the crisis', they haven't solved anything. They've just postponed it.”