Yeah, it is a good move but with a couple of questions.
Most of these studios were already developing exclusively for Xbox, so was it necessary to buy them?
The main question for me is that the number of studios were not the most important issue for Xbox so far. It was their way of dealing with their exclusive games. Phantom Dust, Scalebound, Fable Legends, Crackdown 3... You can also add that the games that do release are not of the best quality (Sea of thieves, State of Decay 2...). It can't be only because of the studios, Microsoft and their orders to the studios are also to blame here (focus on MP and GaaS for example). So, will Microsoft be able to help these new studios to grow and make great games? I'm not sure about that, but only time will tell.