harder to counter if it's on water... You wouldn't be able to launch slammers with your own unit cannon at the enemy's unit cannon under construction.
So now we need naval teleporter AND unit cannon. This isn't even that hard to do Why intentionally second-class naval?
Well actually making a building placable on water is simple, though the tele is more difficult due to ship pathing. (Though that may be improved quite a bit now due to the resize.)
The only thing keeping it from being "polished", is multiple "teleporter" tags in the engine, so naval can't link to land ones. After that, ships already prove to be able to use teleporters, and I have tweaked them in a mod to be reliably jam-free albeit they clip each other in clusters but that is really an old "large naval" problem and since naval is smaller they would path even better and look more polished. The unit cannon thing, really, if it can fire on water with land units, then the cannon probably should only fire amphibious units to begin with. Dox and slammers I mean.