FrogReaver
The most respectful and polite poster ever
So what?
In my profession, I want people who have experience with one thing but I'm happy to take people who have experience in a different, but equally challenging thing - because they have proven that they grasp the big picture of large, complex engineering problems and that they can be trained.
This is the same type of situation. They hired someone to be a designer (a "look at the big picture, ask what-if questions, come up with an idea, and hand it off to the developers to turn it into game mechanics" type of role). WotC likely considers that she has proven experience doing that. It isn't for random people on the internet to second-guess their hiring practices. When a product with her name on it comes out, feel free to critique it.
Friend, This is the internet. Criticizing and second guessing anything, anybody and everything about them is precisely what we do.