Why not freeze-dried?

Ive seen some people disparage the use of freeze-dried/frozenthawed insects for Bearded dragons, but rarely an explanation why, nor do people say "you could but its not best" at least.

I understand Beardies hunt/eat via sight, and that babies need live for awhile. I also know freezing things can reduce the nutritional content, but cant this be supplemented via pellets/powder the same way live are? (I know you can't gutload dead insects like you can with live)

But if they adjust, as adolescents or adults to non-living insects, what is the real problem with it and why are so many people against it?

The explanation why is just what you said. They are not gutloaded. The nutrition just isn't there.
Also, babies don't need live for "a while"...they need it for their entire lives. An all pellet diet is no good either. It's commercial feed. The same way you don't feed a tortoise on just mazuri. It's not complete or varied.
I really wish you would go research on www.beardeddragon.org as I suggested on another thread. You can get all the information you need there in one spot. Lots of people with lots of experience with beardies.

Well, commercial feed in of itself is not always bad, for example harlan makes a complete diet for rodents. There is no professional grade commerical feed specifically designed for Bearded Dragons though. So right off the bat, your feeding your dragons an inferior food source.

More importantly 1) dragons receive a large part of their hydration through their prey and should receive it that way if possible. Baths, dishes, and spraying are not as good as receiving it through the food. 2) They are predators and one of the best stimulation they can receive is to hunt live prey. They never adjust to non-living food, they just have no other options because they are not allowed to hunt outside of their enclosure. Combine that with the poor nutrition and it's a horrible primary food source. It's fine to give an occasional supplement but there is no replacement for fresh veggies and live insects.

So many people are against it because it's inappropriate care for bearded dragons.