With the cool down time that's been added to certain classes (among them swordsman and Thief) there might not be a need to remove the ability to coma using their skills from them; since they can't spam anymore. Furthermore, to be able to coma with skills a class has to sacrifice one card from their weapon to use LOD in tandem with their attack increasing cards, or just use edge. This lowers the attack damage of any melee class that wants to include coma in their skills. The same can be said for mage classes who choose to use Book of the Dead over an elite weapon with kingring etc.
And don't forget GTB, which half the population defaults anyways. More players might now want to default GTB because of skill coma.
Don't get me wrong, coma skills are a pain in the ass, but if we keep them, don't forget that you can use them to your advantage as well, not just your rivals.