Bismarck only got one year of active duty, but the issues wasn't so much what Bismarck or Tirpitz did, but what they were assumed to have done or could have done. Psychology can be more important than real deeds. It was a long flight from UK to Norway, so bad weather stopping the planes from getting a fix on a ship meant that it "could" be out on a trip. And "could" be out was more than enough to affect ther routes of a number of convoys significantly.

And the waiting for them to move out did bind allied resources.

Yes, the wolf packs had a big impact, but at that time they still had big problems with winter storms - it isn't so easy to use the periscope to aim when the weather gets too rough.

In war, just as in all other areas, technology moves forward. It is a long time since battleships had an important role, but during WW2, they where important pieces.