I always thought it would be nice if jobs got traits that changed the effect of their cross-class abilities. Add an enmity effect to Cure for PLD, have Invigorate be partially shared when used by BRD, SMN Blizzara could inflict a short DoT, that kind of thing.

Depending on what they added it could give some jobs better choices with what they set, and others like Invigorate and Swiftcast could at least be different for everyone who sets them anyway.