There's a pretty hilarious video on Consequence of Sound in which college kids admit their ignorance/"meh" to the lineup. Yeah, it makes me feel old, but at the same time, it's all good because it means that my friends might have an easier time scoring tickets.
There have definitely been Coachella years where I was slightly underwhelmed by the lineup, but I always studied it (a favorite pastime of mine), and found hidden gems. And once I got there, well, it's still Heaven, no matter who's on stage.