You seriously want to tell me that Vader would be perfectly okay with a bunch of random-ass Joes having such a chance to glimpse him without his helmet on, or to have regular sneak peeks on the private meetings going on within?
Who said he would have to walk that far to get to the action of things anyway? It could be an extra room separating the main decks from his private chamber. It's not like it has to be a mile long corridor or anything.