My family has one that's about half my height. Which, in a pinch, is an excellent weapon. The only problem is that it's entirely too heavy to carry with you if you have to travel on foot. I know you can purchase ones made of titanium, which would make them weigh a pound or less, and indestructible; but you would have to rely on your brute force to crush the skulls, instead of just the weight of it.
I don't know, all I'm really saying is that if I got ahold of a titanium one, I'd take it- it's a great tool and an excellent last-minute weapon.
they come in all sizes, from 6 inches to 5 feet, so no, they're not too short. find one at a good length according to your height and weight, for me, a two and a half foot is perfect (being 6'1 and 185 lbs) you can also get titanium ones which weigh less
Crowbars make one of the most ideal items to carry with you. Name another weapon and tool combo that works as well? to name a few uses it's a stabing weapon, a crushing weapon, a prybar, a load shifter, the hook at the end can help you to climb to a ledge that might otherwise be out of reach, not to mention the hook end can be used to drag slain zombies from an area. and it has many more uses i am sure.