Morale. Not too many things upset people more than messing with the food. Upset soldiers means uncooperative, unmotivated soldiers. Yeah, MREs aren't great but

Morale. Not too many things upset people more than messing with the food. Upset soldiers means uncooperative, unmotivated soldiers. Yeah, MREs aren't great but at least they're warm and taste like something recognizable. For example, NASA puts a lot of effort into making the astronauts' food things they actually want to eat. Another example, Ford tried to establish a city in Brazil for rubber plantation workers called Fordlandia. The breaking point that led them to revolt wasn't the horrendous working conditions, it was the food (https://en.wikipedia.org/wiki/Fordl%C3%A2ndia#Revolts https://en.wikipedia.org/wiki/Fordl%C3%A2ndia#Revolts). Even old school emergency ration packs had candy in it. You don't mess with the food.