As far as visual arts go, there are several kinds: theater, film, modern art, and photography are the ones that come to my mind, though I'm sure there are more.
Of these, photography and film and the two that we are exposed to most often, and film is the one that we are far most familiar with as a society. Art can be a a form of entertainment, that doesn't take it away from its roots in art. I haven't studied modern art, I haven't studied photography. I don't know the rules and I don't know the form and styles and the high end and low end. So if I go to an art store or a museum, I rely on experts or educated people to teach me things. Walking around a museum and viewing hundreds of portraits and sculptures and mosaics doesn't make me an art expert.
On the other hand, I've studied film, writing, and theater. I have a degree in it. I took classes from experts and educators. I've read books on it. I know something about it. Most people have not done these things. They don't understand the form, the style, mise-en-scene, cinematography, writing, editing, shot sequence, etc. So, yeah, it bothers me a little bit when people try to tell me I don't know what I'm talking about when I say that Nolan is nowhere close to being a great director. He's entertaining, but he's not putting out great films. He shows little respect for or understanding of some of the simplest rules that great directors follow.
Does that mean his films suck or that I know everything about everything? No. Does it mean that people who haven't studied film have invalid opinions? No. But I sure as heck wouldn't try to tell an art history major that Bill Watterson is a better artist than Michelangelo because he made me laugh, or that Jack Kirby was better than Picaso because his comic books were way cool and "groundbreaking."