Hunters can transmog thier weapon between the 3 types of ranged weapons. Im sure they can for melee weapons.
Ranged weapons don't really have much animations per ability. Most are pull, or cock n load. Also maces, axes, and swords share animatione, hence the restriction being lifted.
While Polearms share Staff, hence those restrictions.
Isn't impossible to have one now, with Strength Polearms being added recently and TG adding Polearms to the list.