One of the things people value in a principled person: stability and reliability. If you know their principles and they have shown themselves to live by their principles: you know what you are going to get. You know their actions are not going to swing dramatically by circumstance and appetite. Of course, the content of principles matters, and if a person's principles are bad, you get reliably bad results. But that seems rarer than the chaos and dislocation that comes from unprincipled people.