What About The Average Man?
My Boss's son races 4 strokes at the local level. It seems like the bike is constantly needing the head removed and a grand worth of work done to the crappy thing. He rides a 250 Kawasaki. The bike cratered in its very first moto. They spent $2500 having it rebuilt and it hasn't made more than 3 to 5 heats since before it cooks the valves. They have a pro engine builder doing the work.
The two-strokers on the other hand; they could get by for nearly a season before it was time to go through it and then maybe a piston and wrist pin bearing.
Yes you can get the same power out of a four stroke as a 2 stroke, but at the cost of reliability. The rich teams can afford it, but it leaves the average man wanting for more.