It's not really worth it until Titan and coil. Until those the cheapest food for xp bonus. As an aspiring culinarian it makes me sad to say that. For gathering and crafting it is helpful but not required from what I've seen so far.
I would use food if it didn't cost an arm and a leg to do so.
As a PLD, I'm usually the first to die, and paying 1.5k for
a slice of knight bread six times per dungeon run is nothing
I seriously consider.
As such, I stick to orange juice until I am confident that there's
a realistic chance to down the final boss within the next two tries.
Also, It bugs me that everyone expects me to wear the best
armor possible and buff myself with food, while the WHM runs
around in his artifact gear against HM Titan, and has not even
heard about edible stuff.
No wonder noone wants to be the tank. It's the most expensive
and unforgiving class out there.