One reason why older boats of that size won't have an aft head is the beam was not carried aft under the IOR rule. So the Quarter starts narrowing off very quickly and the head on one side would bump into the galley on the other.
As the racing rules changed and the beam was brought right aft the production boats followed (not the other way around as some suggest). Production boats have stopped at the current beam where racing boats have kept on going to now ridiculousness lengths.... Of beam
Also, of course, as the beam got wider the aft waterline got a lot longer, lower, so none of those narrow sterns that some people adore and I can't figure. But that also means the aft head needs to be higher in the old boats.... But didnt the old toilets need to be below the water level?
As builders say everything is a compromise.
But I do know that an aft head is better for those reasons you describe.
Our first family boat had the head in a cut out of the V berth! Mum and dad had to bail out whenever we 3 kids wanted to go!
With my boat having two heads, fore and aft but only one user (me!) I have the ability to use both... But I normally use the aft head unless at sea then I use the fore head. The aft is bigger but the pump forward worked better at sea.