Healing Magic skill should improve cures regardless of what job you have, and lets be honest - while this is a more important issue to White Mages whose only role is to dish out the cures and support - other jobs would probably get more benefit from this then White Mages.
If, for example, you cured +X more points of curing per cure, where,
X = (Healing Magic Skill -300) * (Tier of Cure)
then we would see a much more noticeable increase on lower tier cures then larger tier cures - even if Cure V cured 375 more points per cure, a 225 point boost to Cure III, and a 300 point boost to Cure IV would affect non-White Mage curing much more.
Keep in mind that this formula is just a basic suggestion that would need tweaking however. Perhaps it would help if someone gave a good suggestion for this, instead of saying that White Mage has no complaints, because a good tweak to how important Healing Magic skill is could help non-White Mage classes out too.