Because he's not some closeted artiste like anon assumes. He is one of the true lifers in the industry that has seen it from the beginning to present and has worked in, and even been instrumental, through most of its lifetime. He is a businessman, producer, artist, writer, director, mangaka. It's a simple fact that the man would have more to say about anime than almost anyone alive even if he'd never actually picked up a pencil personally. He is extremely knowledgeable and well-read on many, many topics other than anime (as opposed to just parasitically drawing inspiration from other anime). The man is brilliant. An old, dickish, bizarre and egocentric man, but a brilliant one.
Thinking Miyazaki is some out-of-touch old crank from a bygone age is the most fucking normalfag viewpoint you can have. It's the hat-tipping teen atheism of anime fandom.