I’d like that too. However, only as an option via triggers in the editor. I can understand that it would be problematic for the regular game in terms of balance.
But it would be cool for custom scenarios.
Although, let’s be honest, would they really be improved with an overhaul?
The genius of the longships didn’t lie in their naval combat power. The genius lay in their relatively simple construction. They were fast, offered little surface area for attack, and were suitable for both the high seas and shallow waters. They offered space and accommodation for a limited number of warriors who were also sailors, and, depending on the size of the crew, could also carry the necessary supplies and, subsequently, the loot.
They were essentially a jack of all trades, considering the needs of the Vikings and their purposes.
They were primarily transport ships, rather than warships. You could certainly fire an arrow or board a ship, but the Vikings weren’t interested in naval warfare.
They wanted to be able to land quickly and almost anywhere (without having to carry dinghies) and leave just as quickly.
So if the longships were reworked so that they only had a certain ranged attack capability with a crew, and perhaps also the “ramming damage” of the Monoremes (to simulate boarding, of course, in a weakened form), then they would be unique as hell.
Longships shouldn’t be able to accommodate as many crew as transport ships, nor siege weapons. Only infantry and archers.
I would take away galleys and/or demolition ships for them. Gunships as well. Under certain circumstances, they could then also be given dromons. Less from the perspective of historical accuracy, more from the perspective of having a siege ship at all.
I think these changes would actually be something unique, which would take this unit and the civilization to another level.