I fully agree with you that more quantitative studies would be valuable, ones that could really isolate valid variables built on solid constructs within a context-rich environment. Also some theory-building qualitative research would be useful.
I have a slightly tongue-in-cheek question for you. I assume that you think teaching skills that promote leadership in children is a good thing. I agree. But consider for a moment what may happen if we do. Do you think that a whole cohort of pupils will grow up expecting leadership roles; would they naturally sort themselves into a hierarchy; or would something else result?