Dave, maybe those racers are simply bad at math? Many are. Buy cheaper tires, race all year . You should save enough to race an extra race or two.
The only downside that I can see is that lap records will have to be reset. Alignments may require change. Nothing huge or costly .
Wheel size may change a little if you want to go as fast as the tires will let you, but you have the option , if the rule change is smartly written.