Zelda: Character or mere tool?

So, this thread comes from a response in the "I'm Linkskywalker. Ask me anything." thread regarding Princess Zelda. Rather than answering there the interesting discussion that is begging to happen I decided to simply create this thread.
So... Princess Zelda

The fact that Zelda is with you through the journey makes this game special to me. It was great to have her getting angry and concerned and helping you through by taking the Big brute warrior, so unlike her.
However after reading the above discussion I wonder, was she really worked enough to be considered a character or is she still actually to flat for that and was more a tool, like an extra item and a goal motivator.

What do you guys think? Just how much depth did Princess Zelda had in this title?

EDIT: I took down the quotes, as i felt they distracted from the thread.

Fair enough. Although I wasn't going for an exact reply to your quote, it just got me thinking about the point or requirements for a character to pass from one point to the other. We've seen in movies how some characters seem to have some depth but they really don't go farther than a few stereotypes. Since lately Zelda can be seen as falling into this, I was wondering how the Spirit Tracks incarnation fares... at least in other members' opinions.