Future Job Abilities, what do you want?
Even though im neither of these roles, it would be awesome if
1. BLMs had access to Doublecast. How would it be used? Well, waiting 3 mins for every Doublecast sounds plausible. How long? 30 secs. How would it work? Every cast you make counts as 2, so casting 1 Fire sends 1 fire, and another immediately after. Could you do double flares? Depends, though there would need to be some kind of drawback if that was allowed, in my opinion.
2. SMN or even SCH had an "Oversummon" kind of skill, that lets them summon more than one pet at a time, at the cost of slowly draining MP over time for a period of 30 secs with a 3 min CD. Would greatly increase the already pretty potent DPS.
3. BRD already has a magic res debuff for bosses which make them valuable in caster heavy teams, but I dont see any love for the Melee classes/jobs. How about a "Symphony of War", where it increases the physical damage of the party. Why not a defense debuff? Well, it evens them out.
I main PLD though i cant think of anything big for my own role. Funny how that works.