There are 3 lobby's that have RR implemented. Cycled Production, A and S class. They aren't perfect, but it's a step in the right direction.
As far as banning cars goes. The cars themselves shouldn't be banned. It's the terrible PI system when you upgrade. Cars should have a minimum grip requirement per class when you are upgrading. This would prevent 1,000hp BRZ's in A class that can't take a corner.
I agree with you about jumping to unrealistic classes with cars. Their attempt was a complete failure with the homologation. Cars should only be able to jump 1 class from factory. The P and X-Class cars in open lobby are absolutely terrible. They should have had their own open track day lobby.