That's something I've always wondered about. It seems like at some point it became trendy to hate on Bose - hence almost every online discussion about them having a dozen people show up to say they're overpriced and sound like crap, yet I don't think I've ever seen one of those threads where someone actually names speakers that are better AND cheaper.
To my (granted mostly non-audiophile...though I am the type who insists that vinyl sounds better...) ears, they've always sounded pretty good and aren't that expensive compared to most high end offerings.