It's not really anything new however. The Aboleths were previously described in 3.x as creations of (by whimsy or design) Piscaethces the Blood Queen, an entity from the Far Realms.
I should have been more clear, the departure was that they are not necessarily intelligent, just acting out of some weird set of complex instincts. Which isn't a terrible take on things, just not quite what I'm use to.