Im a battleship player. I liked subs , I think that the will 'complete' the game and should be in the random battles. We are sunk and destroyed mainly by cruisers and destroyers , why not by subs also?
But WG should change some things.
1. Abolish the ping. Its highly unrealistic, was never used in real battles and makes gameplay very hard. Torpedoes should be like the destoyers , no guidance
2. In the U69 that I played you cannot fire the torpedoes one by one , its another thing that should be changed. even in the movies captain says 'tube 1 fire, tube 2 fire. tube 3 fire..'
3.no more than 2 per battle.
I think that it will be an historical injustice not to include subs in the game in full tech tree for all main nations.