Let's not dump the baby out with the bath-water people. Pain can be a great motivator. Remember pain =/ abuse. There's a difference between a bare-knuckle rumble and a belt across your hand.
Our Prophet (SAW) would be strained whenever revelations would be revealed to him - described as face turning red, sweating, and his body getting heavier. The Qur'an is sacred text, and juvenile/careless behaviour should not be tolerated when teaching it.
It has to be burned into your psyche - and either you'll motivate yourself for that or the macalin/parents will.
But being who were are, we've taken discipline to its extreme. Teachers should not take their frustrations out on their students, which seems to be the case in a lot of dugsis.
Punishment should be meted out as a consequence for bad behaviour, and should be exclusively physical (so no humiliation), fair and systematic (no favouring), and consistent i.e. no cashar = 3 cane hits, talking/lateness = 1, etc. Not choke-slamming into table one day, painful power-poses the next.