Responsiblity is a subsection in the book, as is initiative (i.e. being proactive). Neither are roots though. Why be responsible? Why take the initiative? Why do those things matter?
Curiosity derives from a couple of the principles, but it's also not a root principle. Why be curious? Why does curiosity matter? What gives rise to it? What's the deeper motive behind curiosity?
I guess you could say I think deeply about stuff like this because I have nothing better to do.
I've always been attracted to problems that were interesting and challenging. Mapping consciousness seemed like a worthwhile pursuit because it has the potential to endure. If I die and retain some form of consciousness after death, I'll still be able to use this model to continue growing in the afterlife. I don't even need a physical body to apply it. I just need to be conscious.