I suspect that would be a few kinds of buggy. Bracelets don't have any movement to my awareness, they just sit inert on the wrist, and may not be able to move with the hand animations. Also, both gloves and shirts can have a "hide bracelet" command that would mean your hypothetical nails-as-bracelets would randomly vanish with anything that would require a normal bracelet to be hidden.
That said, something they have been adding as hand gear lately which can and should be a bracelet is watches. We've gotten two from Island Sanctuary as hand gear so they can't be combined with gloves.
Isn't that exactly what they are doing with the graphics and dye upgrades?