Geez people, I am a little surprised at the apparent venom here. Or thats what it sounds like to me. Of course I am still working on my first cup of coffee.
ALL mods are always an option that you can choose to use or not.
Personally I think the idea of invisible mines is cool as hell.
Adds a real sense of danger and suspense when a minefield is in the area. I would leave them at full strength. I can't recall any sub or ship, from all my studies and reading, that observed a submerged captive mine from the bridge. Or in the case of just a sub, while submerged. Only the ones that had broken free and were floating were seen at all.
Penetrating enemy harbors should be a knuckle biting sweat-fest.
As for friendly harbors thats what the escort ship is for.
Good work Der Teddy Bar