You know, strictly logical speaking.
Why should you be no longer well fed, just because you bit dust and are revived at the start of the dungeon.
On the other hand. You don't HAVE to eat the food, it just makes you better to a certain extend. If you suck with food, you suck without. (Yes Marmeladesalsa it also works this way)
In my culinarian way of life till now I have barely found food, which would be mandatory for grouped events. A lot of this food is quite a life saver for solo duties.
If you don't trust your group to do a dungeon without wiping, don't pop expensive food.
And 6k as expensive food? A single Pop of food in FFXI could be WAY above this, TANK food, so if your healer sucked, you were in more than just one kind of pain.
I saw parties dissolve because everyone expected DDs and Tanks to eat the best food there is and those people dieing all the time because the Healer was busy watching Jersey Shore or shit.