It is a neat way of actually showing how a godlike being might create something that is itself godlike, and it is no less valid than saying the First Ones created the Shadowlands and the Pantheon with it.
The issue I see is more on how the fact that they look like what we know implies a sort of intent on how they would act as well. Kyrestia was always going to be somewhat stubborn and unwilling to change, Denathrius would always be untrustworthy, and Zovaal would always end up being evil.
Taken in a vacuum it's a wonderful piece of high-fantasy that could drag a story in a myriad different ways. The issue is more that WoW isnt the kind of game that can support such a concept. It's more likely it will end up reductive and making the world feel smaller, instead of what I assume to be an intent to just make a cool setpiece.