Egos are always part of the reason a band breaks up, unless there's extenuating circumstances, like for instance Led Zeppelin. They weren't going on without Bonzo, so that was that.
There's a documentary called Pink Floyd: Behind The Wall and it goes into great detail about how the tour was crafted, from the actual "bricks" used on stage to the puppets and the graphic imagery (the fucking flowers, the marching hammers, etc,.) I think when David said it was ridiculous, that was him being nice.