The Useless Princess

Dear Hero,

''Guess what. I was kidnapped. What a surprise, right? You know the drill.''

Signed,

Some Worthless Princess

The princess who seems to be totally worthless to her kingdom, let it be that she does nothing all day or that she Gets Bowser'd on such a regular basis, It's Not Funny Anymore. If it's kidnap that's the issue, the Hero, being the benevolent warrior they are, always bounds to the princess' rescue, despite the same old kidnapping story seemingly endlessly recurring.

Rescuing the Useless Princesses is a very common End Goal in older video games. This may be the only reason why the Useless Princess is important to the game: she gives the Hero a reason to be heroic and go on their adventure to save her. Even though she may not serve her kingdom in any apparent way, she must be saved from the clutches of the Villain and not simply be killed so then the Hero can be done with her, the Villain can get their way, and the King can have another daughter who's hopefully more useful than her predecessor.