A regular bullet puts a hole through you unless it strikes a bone. A hollow point splinters and creates multiple areas of damage thus more life threatening.
They are actually more humane, in that the "shock" transmitted to the person being shot will many times stop the attack with only one shot... and there is a chance that the one shot might not be fatal.
If you shoot someone with full metal jacket bullets, the shock is much less, and more shots will be required to stop an attack. More holes through a person tends to ensure that they will not survive.
I've read stories of criminals shot in non-lethal areas, such as the upper arm, leg, etc, that were incapacitated with one shot, who went on to survive with minimal permanent damage.
All law enforcement agencies use hollow point ammunition for those very reasons.