Because the more fetishes you cater to, the more people will buy the DVDs and merchandise. So you don't have to put a lot of effort into actually making the show GOOD.
masian said: why do they ALL have four ears in this show?
The animal ears and tail grows on them when they use their magic powers, and if they didnt have human ears, they would be totally earless when not using magic, thats why. + because its for fanservice.