Not healthy? Some of the best game ever are exclusives. Look at Sony.It's not good for the industry because it's a pretty anti-competitive move. Consolidation of these big publishers is never healthy, especially when one swallowing things is MS. And MS removes someone who was deteriorating their DX lock-in.
Personally I'm glad Microsoft is buying studios. Sony now will try their hardest not to be overshadowed by Microsoft and will increase the quality of their already great games. Microsoft will answer with even more great games.
And Bethesda will be forced to test their games now because Microsoft won't want one of its first party studios to look bad next to Naughty Dog or Insomniac lol