Certainly the fetish for burring engines in the wing circa late 30's/40's didn't help the Brabazon. To my memory the only big production plane with wing-buried piston engines was the B-36.
Speaking a a maintenance person I was told they were very difficult to maintain. Lots of manhours. The extra weight of gearing two engines together (Brabazon) or incorporating a cooling fan for the pusher configuration (B-36) are a weight penalty you don't need.