A module, by definition, adds a feature to a Drupal installation. A well written module often provides administrative touches such as the ability to 'hide' the feature from certain user roles or because of a particular site configuration.
This is all well and good, but a problem can arise for the administrator when testing, if the module supplying the feature fails to supply some kind of visual feedback to indicate when it is in 'feature hiding' mode.
Without this indication, the administrator cannot tell the reason for the disapperance of the feature - "Hey, what's happened - has the xyz module crashed? why isn't it working?"
I think it is important that the out-of-the-box, default setup provides some clue for the site administrator as to the status of the feature-adding module - especially when the new feature is intended to add something to an existing form or forms.
As an example of what I mean, many Drupallers seem to have had an incredible amount of trouble with the CAPTCHA module's add-on form which stubbornly refuses to appear for site administrators if the option to "Add CAPTCHA administration links to forms" is not selected. It seems that many jumped to the conclusion that there was some mysterious bug at work.