I honestly don;t know why I felt the need to argue otherwise. I'm going to write an angry letter to Anheuser-Busch.
The question has long fascinated me as well but I haven't seen a very good explanation. A couple of suggestions I've come across have to do with (1) urbanization and (2) a sort of cultural glorification - but these seem very inadequate to me.
My explanation might not even be in the ballpark, but that's the best I've come up with so far.