Drac card does not only proc with physical attacks.
Example, I leveled an aco four times, twice as regular, and two more times as high aco.
The second time with a high aco, I had a quad drac mace, while healbombing, heals were not only giving me the bonus exp from killing the mob, but they also were restoring my SP, so leveling a high aco to job 50 again wasn't making me want to gouge my eyes out.
In the essence of reasoning, dracs are to pretty much prevent people from going from 70~99 in two days of Niff with their wizards/priests. Though, of course it is often used as a leeching weapon, it has a few uses in combat weapons as well, unless you have nothing but dracs in it, SG books, for example. :>