Self-heating meals, such as Omeals or Heater Meals, are an excellent way to enjoy hot food when you're camping. This is especially true if you are backpacking and looking to keep your pack weight as low as you can. When your food cooks itself, then you can possibly skip carrying a bulky camp stove as well as the fuel for it too.
Meals that are self-heating are not really foods that cook themselves, though, to be technically accurate. The foods are already prepared and cooked; they just get reheated, so they are more pleasant to texture and taste. Warmer food is also easier for the human body to digest, and when you're out on an adventure, your body can use all the help it can get with absorbing nutrition.
Self-heating meals are often MREs or at least derived them. Meals-ready-eat are derived from originally military rations that armed services personnel used for nutrition in the field. Many came with self-heating options, although many also relied on a portable heat source for the heating.
Whereas MREs or self-heating meals if you wish to, might come with their own heating source or were usable with a separate source, a self-heating meal has all it needs in one convenient package.