the over water thing has no relevance. in europe its been 1:50 for as long as I can remember (10+ yrs). It used to be based on the number of seats installed but now it isn't.
a number of bus operators including easy has blocked off 6 seats in the 319 and have approval to run with 3 dollies just like a 149 seat 737.
we don't like it but its just how it is.
i think its just a case of oz coming into line with the rest of the world nothing more than that and while the bean counters can put that argument up showing precedent and casa accept it thats how it will be.
its all about money now, nothing else, anywhere else.