This idea comes from Guild Wars 2. In that game, when a player goes into "Crafting Mode", they have access to all items in their inventory as well as all items in their storage locker (in FFXIV, retainers).

I understand this could be easily exploited in the open world. I believe this access would make most sense while in either A) Towns/Sanctuaries with Summoning Bells, B) Residential Districts and, maybe maybe C) All Sanctuaries
(There really should be moogle-mail and summoning bells in all Sanctuaries anyway, imho)

The reason is it is quite cumbersome, especially with cooking, to:
  • Open the crafting menu and review what I need.
  • Open the retainer menu
  • Grab what I need, craft it, put everything away.
It takes almost as many (if not more) button clicks to prepare and put away the ingredients as it does actually crafting. Add to it that many items have the same icon and it just takes a lot of time to craft something that should be very quick.