If I were to wager a guess it would simply be that these jobs are Mages, whose roles have very little to do with melee combat. They are given staff skill so that they have the ability to hit things with a weapon if they absolutely need to, but it is no surprise that they do not have access to higher tier combat abilities like HQ WS.

Blm and Smn are not Stave Masters. They are non-melee jobs who have a basic proficiency in staves because it would make even less sense to give them any sort of proficiency in anything else.