They are great for small dets (recce, OPs, Sniper etc) out for a few days at a time to cut down on weight. IMPs are bulky and can be resource intensive to heat and resupply not to mention they often many aspects of the mesh require water to make it edible.
The survival gummies are a great pick me up that you can carry and consume at anytime. LMCs are similar but a bit bulkier.