This world is based around unnecessary things; I'm sure you've noticed that much by now. But this much is necessary by nature, really; humans have spent their entire existence as a species coming up with new and creative ways to kill each other - and when we aren't getting creative, we're at least getting more efficient at it.

So give us a world full of magical animals that are capable of maiming people, and it won't be long before someone's going to use those animals to do exactly that; it's a logical progression, as people go.