For the safety of the public and for us. Their top canines are serrated, and leave nasty scars, and since our lemurs do come in contact with the public we'd rather be safe than sorry. Really, it's cosmetical and is not any different than de-clawing cats. We go to the top lemur and coati vet in the nation, so it's not like we're de-fanging them in our back yard.
comparing it to a barbaric practice that has been banned in a lot of countries isn't helping your case. people that declaw their cats deserve to have them taken away unless its for a serious medical reason.