You know, I find it almost funny that most Women in Nanoha are nearly the same busty body type.
I believe it has to be connected to having above average magic powers. This might also explain why 95% of strong mages are women, with only a rare man among them. Those men would be mutants who somehow gained decent magic reserves without growing boobs at the same time.
Counter counter counter point: Pre-StrikerS Nanoha and Fate, who have above average magical power without being busty.
Umm... Yeah. They were kids. Female babies aren't usually born with big breasts. They grow eventually during puberty. What I meant is if a woman's genetics dictate high magic potential, it's more often than not coupled with developing a large bust. It's a linkage disequilibrium in the terms of population genetics (I avoided saying this in my earlier comment because I wanted to make the joke about men).
Also, I don't get how "purposefully designed to be a loli" is somehow supposed to strengthen your "boobs equals power" argument.
Hayate's knights are frozen in time, as far as I know. Vita will be forever a loli, or at least as long as she exists. I don't think she will grow up to adulthood.