I agree they are ugly, but I would nominate the old London Daimler DMS / DM / D class as being the ugliest ever - they tried to emulate the front end appearance of the Trolleybus, but failed dismally in the attempt...
I think the DM/DMS wasn`t all bad, not from a travellers perspective. They had a poor infrastructure around them. Repairs were a problem as parts were unable to be sourced around LT garages. Whereas with the RT/RM they were designed around Aldenham works and had fewer problems. The routemaster wasn`t particularly successful at first and wasn`t generally liked, but LT had to work with it, where with the DMS was not seen as politically viable and so withered away. It could and indeed should have been so different.