Sure, it's the adventure and the chasing and the introspection at the Art Institute that makes Ferris Bueller the classic that it is, but let's not forget the essence of the character.
Broderick's Bugs Bunny-esque weisenheimer is incapable of downtime - so when waiting for Cameron to show up with a ride he'll make a number of costume changes and entertain the audience with gags. From an audience perspective, we get the feeling he'd be doing this whether "we" were there or not.
