Why is going 30MPH on an e-bike more dangerous than you going 30MPH on a human powered bike? If they should be licensed and insured, then all bikes/riders capable of 30MPH should be also. In my estimation, it comes down to being responsible. You may say that e-bike riders are more likely to be irresponsible but there are plenty of bike riders that are as well. Punish the bad actors and leave the responsible people alone.
Not sure if it is still true but years ago, mopeds did not require a license in most places. The e-bike is the moped of today. Should there be some rules and guidelines? Of course.