Food's only use in 5e is when it comes to spending gold on rations for when the party has to travel lol. Other then that there are like a grand total of like maybe 2-3 feats (Some UA ones) that are related to food, but their effects are fairly minor (Regaining extra hit die during I rest I believe is one of them).
Giving food the ability to heal is a bit wild, as it kind of makes Clerics, Druids, and any build that is related to healing...irrelevant. On that matter, there's a reason healing potions exist? Why should food do the same thing as a potion which in 5e has a baseline cost of 50gp?
Game is probably balanced towards 'play the game you want within arbitrary reason' and not everyone likes Shadowheart or wants to roll a cleric/druid etc. Food also weighs a lot more than potions such as the pig's head being far heavier than the rest, so horay for inventory management.
And if you do have a 'healer' in your party, they can now do other things which are far more impactful anyways such as providing advantage and having spells like Bless etc.
All those are just resources which need to be controlled and taken account for (which they have a limited quantity of).
