I believe traffic lights are always trying to solve a capacity issue - where the roundabout has hit it's maximum capacity and is suffering some throughput issue, which tend to sort of get exponentially worse. With traffic light sequencing, particularily dynamically, there is always a way to even out the flow - prioritize a flow that is backing up undesirable or give a particular entrance fair chance to enter the roundabout.
Though once there are traffic lights on every entrance, plus traffic lights mid roundabout and some/all exits, and explict lane markings and merges I think it's not a roundabout.
Slowing down is important though, as it give drivers time to think and react. Whether they choose to use that time correctly is a problem, but hopefully some or all of the other drivers can use patience and avoid an accident. Where accidents happen, I see it's often from mistakes from two drivers, and it's relatively low speed. Better still, accidents are at shallower angles, so injuries are rare. I've heard an statistic that could well be fake that roundabouts have more accidents, but significantly better outcomes overall.