Well someone has to pay the upkeep for the animals! Some aquariums and zoo's do very important research and are a major help for various disappearing species. If that means the dolphins need to "jump for their dinner" or the bears need to smile for the camera, well, someone's gotta help pay the bills.
I'd have to consider each facility on a case by case basis. Just making people aware of the animals and fishes is a good thing for the various creatures on earth.