At max level people stop to drink far more than they stop to eat. I’d say close to 0 people stop to eat in M+ while some healing specs have to slip in drinking.
We already have follower dungeons to give ourselves mage mana biscuits whenever we want, so there’s no real reason to preserve a mage’s role as free food dispenser when they could simply make recuperate replace the need to eat or drink to recover entirely.
Recuperate already has the same restoration speed as eating mage conjured food, it just does it in 10 second intervals for 50% instead of 20 seconds for 100%. There really doesn’t appear to be any reason why it shouldn’t include mana outside of wanting healers to purchase vendor water or spend 10 seconds every login to enter a follower dungeon to get free mage food.