One thing I intentionally ignored were existing sea routes. I don't see a reason to take them into account, because they were just as arbitrary. So the argument "this makes an existing route longer" holds no water to me, because at the same time it will make other (not-yet-existing) routes shorter, or even possible.
But this argument makes little sense.
The existing sea routes were, every one, drawn along what made good sense as trade routes. They were from city to city, and most of the city pairs were the closest 2 cities spanning a particular body of water. Now, obviously, long routes like from the D'Haran islands up to Morek/Astrum don't make sense to try to preserve as a single sea zone—but short routes like from Paisly to Port Raviel, or from Libidizedd to Eidulb, make perfect sense. (And I would note that Libidizedd's two sea routes
have been preserved as a single sea zone.) I don't have a problem with upsetting the old order for good reasons, but upsetting the old order simply for the sake of it is silly.
In short, long-standing IC trade routes like the old sea routes
should, in general, be shorter hops than other trips of similar distances. That's why they would be trade routes in the first place.
