"Right. Smaller flatter bottomed sand floors are much easier to maintain and aren't as susceptible to having the sand wash off a steep face because there isn't any steep sand face---just sod and grass that these days have massive pins in them to stablize things. Can't put those massive pins in up-swept sand though unless it's to fasten down the bunker-wol or Sandtrapper just below the sand.
Between geotextiles (bunker wol, sandtrapper and others), pre bunker drainage networks (in this case), more intensive internal bunker drainage sytems (2" interceptors in the lip through to tight herringbones), or simple water diversion around the bunker (raised lips to mild swales). There is always a way to keep classic feature bunker the way it was, without subjecting yourself to washouts.
We used all of these at Capilano to keep bunkers, in particular the front bunker on the 9th, which has a series of these techniques to preserve Thompson's bunkering (the green falls steeply directly into the front bunker).