6 months ago:
Ehhh... I've got mixed feelings about this. I know that they did it to balance out the Dragon type. My big argument against it, though, is that a Pokémon type is a really fundamental thing in the Pokémon universe. It's a bigger stretch, I guess, to every few years say "oh look at these hundred-or-so completely unique animal-esque species we just discovered even though they're suddenly widely spread amongst people and have been for all of history!"