Fish-
The two points that I think cover this issue are this,
The biggest problem with wakes, poor driving, etc, generally come from the Tuna boats, no question whatsoever.
The other point you made about cleaning up the environment is definately a valid one, and I for one agree, however, I will bet you my next paycheck that my 135 Optimax emits far less pollution than the 90 hp carburated 2 stroke running next to my boat, yet my 135 opti would be banned under your idea, and the stinky 90 would be perfectly legal.