I was always lead to believe that Ball ammo was issued to the Militaries of the World due to the Geneva Convention and rules of engagement. Ball ammo reduced the hydrostatic shock effect and therefore was more effective on disabling the Enemy rather than killing him. I was lead to believe that an Enemy that was disabled, took more troops to take care of him ( medics, litter bearers etc) than just leave the remains and move on in the battle. Thus, the reason why troops were shot with multiple rounds and kept on fighting.
I have carried and used ball and hollowpoints in many ways. Every other round a Ball or hollowpoint, and then just either or in a full mag. There is plenty of good stuff out there, but you need to practice with different brands and stick with the most reliyable round that suits your weapon's taste. Just my 2 cents worth