Well, it's clearly a personal thing. Those who wanted to watch did. Those who think it's OK to feed giraffe meat to lions will carry on thinking so, especially when the animal has been well cared for all its life and killed in the most humane way possible.
Butchering (dissection of dead animals) is not looked on as undignified by everyone but as something that has to be done with a dead animal if its meat is to be used as food. I ordered a leg of lamb for xmas once and the butcher sawed the leg bone off for me so that the joint would fit in my oven. I watched him do it and was not upset. It never occurred to me to be upset. No-one and nothing was being hurt. I used the bone to make soup stock.
I suppose the zoo keepers didn't want to give the lions the whole animal, though I don't suppose the lions would have minded. The dismembering would have been a little less "dignified" perhaps.