1. The suspect was not seriously injured.
2. He was dangerous and suicidal, firing the weapon in the air as he walked through a residential neighborhood.
3. He had already robbed a convenience store in Tucson, broke into a church, invaded a home and stolen a car.
The take-down was preferable to shooting the suspect, because officers don't shoot to wound, they shoot to kill. There is always the danger of innocent people being struck by stray gunfire, and no one knows what the man in his mental state would have done had officers squared off with him, guns drawn.
It is unconventional, perhaps, but the suspect is alive, he will face the charges he deserves to face, and perhaps he can get the help he needs while locked up. If he was shot dead, none of those opportunities would exist.