Why would or should any military or government for that matter have a problem bombing or attacking anyone, any building, or any organization who is directly aiding and comforting the enemy in a war?
Yes, it was a hospital. Outside of that, what makes it any different than any other building that the enemy captures and fires on the government or coalition soldiers? Docs without borders knew it was dangerous to go to the front lines and practice medicine in a war zone. It's like you running out in the middle of a street during rush hour traffic. Sure it's tragic if you get hit, but unless you are an imbecile and generally do not know any better, its your own fault. Why should I blame a driver for your death?