Meeting, ready to eat. These can be eaten cold. No water is required for preparation.
They are expensive on a money per calorie basis. They are heavier than dehydrated or freeze dried rations. But they are ready and cooking optional.
I keep a few for bug out bags, car kits and potential need to eat on the move or without cooking. They are a medium term prep for special circumstances.
I do not store then for long term preps or for everyday food distribution issues. They are simply too expensive for that. For the cost of a single case of mre rations I can buy
20# of rice, 20#of pasta, 20 pounds of beans, 60 cans of veggies and tomato sauces, 30 cans of fruit, and a little meat and condiments and feed a family of four for a month.
So except for special circumstances I not a fan of MREs, but they do play a role in preps, a small role.
For bug out food I lean towards backpacking type foods as they are lighter. You will need water sources while traveling anyway but am mre could give you a break.