TL:DR something like War Thunder's X ray thing (damaged modules will be colored red, white = undamaged) after we get damage system 4.0 and open world.
story time:
I finally installed the game after lurking here for a few days, 1st round = best round, sank a Constitution with a Yacht Something I noticed while playing my crappy Lynx with only 4 cannons tho is that after a bit of fighting I start to loose cannons --> no idea where my shots will come from --> miss at point blank trying to double a Brig from the rear. I guess its less of a problem on bigger ships with many cannons, but once we get open world and smaller ships become popular it could be a nice thing to have.
A detailed visual destruction system would remedy this too but I guess its more complex to develop
(*small ships in the sense of less than 6 cannons per side)