I don't mind bunkers that lead directly into the water. After all, they are each considered hazards according to the rules. But in nature, rarely does water change directly into grass or some vegetation, it often starts as sand/dirt and then works into grasses. So, in that way, its more natural. Some are done better than others of course, but overall, I think they are fine. And to clear it up, you most likely don't actually lack sand under your ball, the sand there is just compact because its moist.