I did not keep up with Minecraft over the years, only just looked into this now, but yeah, this seems so arbitrary. There's a mob (armadillos), then an intermediate item (armadillo scutes) and the only usage for that is crafting wolf armor.
Whatever happened to not having a million different items? Like, that's pretty much game design 101, to combine mechanics where possible. They could have allowed equipping a leather body armor on a wolf for the same gameplay mechanic.
But it really does look like they wanted to add some animal for the publicity and then needed to shoehorn any purpose at all for it.