The advantage of purchasing individuals pouches is obvious. You have more of a variety. You can take these extremely lightweight pouches hiking or backpacking. You can also eat the food right out of the pouches.
The disadvantage to purchase pouches of freeze dried food that aren't protected in food buckets is that they have a lot shorter shelf life. Typically the shelf life for pouches is 1-3 years depending on the package, contents, and storage location.