One of the issues is that the Russian sub mod is only a mod - the base game isn't designed around a Russian campaign or Russian tactics.
I always assumed the reason I was the only friendly asset on the map (besides aircraft/satellites) is because US Sub doctrine (as far as I know) doesn't use wolfpacks - or didn't during the periods modeled.
Even if there are other subs in-theatre, we aren't coordinating missions.
Then again, it could all just be concessions to gameplay; if my allies got the war done for me it wouldn't be much of an experience for me. Likewise if I only ever came up against lone subs, that wouldn't be particularly challenging compared to the wolfpack/convoy/bastion missions.
