-Perks for the following day. Depending on the food you choose, you get related perks such as (extra spell slot, extra HP, extra what have you). It could depend also on the characters. Limited Status ailments could also be fun (hangover until next short rest if you just had wine for instance).
We definitely need it. Right now, it doesn't make sense to have your inventory completely filled with different types of food if they all do the same thing. Either they differentiate the items in some way, or they reduce their variety.