Although many people might be more tempted to bring there cars if you limited power just as many people might be put off if you do limit power! I would be less tempted to run my vintage car because i would then have to resolder the 5 wires onto an esc that runs brushed motors, swap over aload of stuff and i cant be bothered cause ive only just put all the brushless gear in! (again!)
You could always have 2 classes in the same race? like at le-mans for example?
The poll results show the direction that needs to be taken. Listen to the customer!