Yeah, it does take an active mind to not be put to sleep by such films. They're not for the passive consumer who awaits to be entertained with plot twists and/or explosions. In general, they're not there to entertain anyone...
Careful what you say about movies that put you to sleep like that. I thought the same thing when I first watched Koyaanisqatsi... now I've seen it upwards of 30 times, probably :)