... not everyone is going to move the way an aikido person will move ...
It's the purpose of my practice to make people move the way I want them to move. Whether they practice aikidō and know nikyo (or any other technique) or not.
I experience this to be possible when applying nikyo as a way of connection to uke which gives me control over his structure to a certain degree. Inflicting pain just locks up ukes structure and if he does not know how or where to move, he will just get stuck and "break up" if tori does not halt his technique.
I don't understand why it would be "more martial" to inflict pain? To me the criteria of martial effectivness is whether I can handle an aggressor or not. I think aikidō to be "designed" in a way that it works by using things like body structure (tori's structurer affects uke's structure), contact, inner movement, ... . To my experience pain is not (never) what makes aikidō waza work. It can be added if one want's to. But pain is not the vehicel of (technicly understood) aiki, I think.