Maybe I couldn't resist posting this suggestion (sorry) because "having something to protect" is such a staple of anime. But - there's also a good case to be made here.

An analogy is motivational posters. Animes are essentially motivational posters for "having something to protect", since after all this is often the moral of them. Nonetheless, they have advantages over motivational posters:

• Higher budget. They can last hours, have animation instead of a single phrase, etc.
• They follow narratives (Hero's Journey, etc)