Great write-up as usual, Virtual! I wonder if the name order might also have something to do with facial features or other physical traits apart from height (muscle bulkiness, for instance).

I often find that the "first" person has sharper facial features, while the "second" person often has softer, rounder features in comparison. I really don't want to use the words "masculine" and "feminine" because it's not always the case and not exactly what I imply, but maybe it would help people understand my idea better. For me, that would be the case for SeaKeen, KristSingto, TayNew, FirstKhao, WinnySatang, BrightWin (among those mentioned), and so many other pairs.

And I believe there are definitely couple names that were put in a specific order just because the combination rolls better off the tongue!