I wouldn't be too quick to dismiss them so. Sure, they liked to actually have some fun with their music (and, of course, avoid the dreaded "rocker who wants to change the world" syndrome) but they also had their serious moments. I mentioned the album Innuendo before, and most of it has an...
IMO, I'd consider Queen II to be the pinnacle of their recorded output, although Innuendo is a VERY strong album, even moreso considering it was their last proper release...