A drunken, mean man with a hammer was shot and killed by police last night.

[mythology]

19. One good hit to the head with a hammer and a person can die

If you get close enough to grapple with the guy, you're close enough for you to get killed. Nobody is Batman and can disarm any armed assailant in hand to hand combat. These cops retreated, repeatedly asked the guy to stop and drop the hammer. He didn't. From the information presented, this doesn't seem like the cops were excessive. Maybe if the guy weren't drunk but was instead having a bad reaction to medication or was in a diabetic shock (or whatever that is called), but there's not a cut and dry 100% perfect system to tell every bad guy from every good guy. If you want proof of this, go find a psychology lab at a university and see if they are doing a study where you are shown facial pictures immediately followed by a picture of a gun or a tool and have to instantly pick if the second picture was a weapon or a tool. It's a hell of a lot harder than it looks.

Were there alternatives? Almost certainly, but those alternatives include a greater risk to the officer and others around them. As others have noted it's really hard to hit an arm or a leg and it doesn't always immobilize an opponent. Plus you increase the odds of missing and say hitting a passerby or into a nearby house.

As for the idea of tazering the guy, I don't know if these officers had tazers, but there are issues with giving cops tazers. I saw a study from Australia (I believe) that found after giving officers tazers, they used them in many more circumstances than they would have used guns and it didn't really have an impact on the number of instances of police gun use. So it resulted in seemingly more police violence.