I think they are kind of a great fit. Yes, Bonnaroo is a lot of hippies or hippie wannabees, but there is a very diverse group of people. Radiohead is one of the few alternative/rock/whatever bands that some of the jamband fans like. Having said that, I was at Bonnaroo last year and it was unbelievable how well some of the non-jambands were received. Modest Mouse, Secret Machines, Rilo Kiley, Kings of Leon all had great crowds (packed, in very large spaces) and the people loved them.
For these bands it's great, because they are exposed to an audience who wouldn't necessarily go to a club to see them.