One time I was waiting at the crosswalk and the light was red and also the crosswalk light was showing I shouldn't cross. There was a guy stopped at the light and my spidey-senses told me this was an idiot. Sure enough the light turned green and the signal indicated I could cross. So the idiot guns it and makes the right turn right in front of me. There was no traffic, the guy could've turned on the red at any time. But instead he waited for the green so he could cut in front of a pedestrian (which is illegal) and put someone's life at risk. If I hadn't sensed he was an idiot and just stepped out onto the crosswalk when the signal indicated, he would've slammed into me.

So yeah, making it illegal to turn on a red puts lives at risk. Being able to turn on red makes drivers pay attention to the traffic and pedestrians a bit more while at the red light (because they're looking for an opportunity to make the turn) instead of mindlessly waiting for the light to change without paying any attention to whether there's pedestrians crossing.