The best superhero stories are, in actuality, about internal conflicts. In spite of the razzle-dazzle of super powers, strange creatures, other-worldly invasions, and science fiction marvels, the action in these tales is best used to mirror and drive the inner struggles of the protagonist. Whether it's Spider-man's struggle with responsibility and guilt, the X-men's bid for acceptance from society at large because they have trouble enough accepting themselves, or Mr. Incredible's mid-life crisis, that's what these movies are really about, even when it looks like a guy in a mask fighting a villain on a bridge.
Big Hero 6 understands this, and while its surface is a basic superhero team yarn celebrating science and the power of friendship, it's actually about a boy's struggle against grief and helpless rage.