As a user, those old posts can be helpful when I am looking to solve an issue, but I can see why auto-closing is important for developers—there is no need for me to be able to add to the post, I can start a new one and cite the old one if that seems useful. The ability for the developer to reopen an old post makes sense, but I am sure that it is the exception, rather than the rule, so I would not change auto-closing, just give developers a way to override as needed.