And that is a major point of this episode. In the original series, the Doctor rarely made mistakes. Maybe little ones, to create tension or a cliff-hanger, but never was the climax of a whole story hung on his error in judgment.  In “The Unquiet Dead” we see the Doctor is fallible – he’s not right, all the time, though he likes to think he is. And while later in the episode the raging dead people does seem a bit camp and lacks tension – especially with the makeup – we are really there to see the Doctor realize his mistake and realize that his decisions can directly cost innocent lives. In a later episode, we see how this affects him - and makes him question his own judgment.