I can see why they wouldn't stack with gauntlets, incidentally. You're not punching with them, so much as using them as a kind of sawed-off shotgun with the taijutsu skill used because of the extreme close range. Seems logical enough.
I've been conceptualising it as "You have the option to use gauntlets, and this gives you additional opportunities to attack where you couldn't without them. Rings also give you such opportunities, and the sets of opportunities they grant do not perfectly overlap. Hence, they give stacking bonuses to attack."