I never understood it either. I agree vB looks childish and amateurish and it's always been my experience that it is more time consuming to read a vB community because there seems to be transition pages for many more functions as compared to UBB. Also all the added graphics slow down us poor old dial up users.
I've been an active member in a few communities that switched to vB and soon after I've and many other members left to never return again. It may be faster on the server, but for the average visitor it is anything but.
