Probably banned because it might upset people. It seems to be a pretty toucy subject especially among furries.
Never said it wasn't cruel.
Tho, in my opinion, a tail made from a fox that got to be a fox wouldn't be (as) cruel. I have nothing against hunting and/or taxidermy. (A tail made from a fox that died from natural causes wouldn't be cruel at all.)
Fur farming, on the other hand, is pretty much just pure cruelty.
And no, foxes are one of the least endangered species there is xP