My pet peeve is the complete lack of lightweight packs with decent suspension for children. There is nothing between the "standard" packs made of heavy bombproof materials and with at least a pound of extra pockets with zippers, fancy trim and other heavy and useless items, and a few frameless packs in small or extra small size. The LittleLightGear packs are great for small children who carry only their wraps, snacks and a small water bottle, but don't have enough structure for an older child who wants to carry all his clothing, sleeping bag, pad, maybe the tent poles and stakes and maybe part of their food or their own fishing gear.
My grandkids cannot use frameless packs; they've tried. They have pressure-sensitive shoulders (like granny, must be genetic) so that even a light load requires transfer of nearly all the pack weight to the hip belt and load lifters to take the pressure off the tops of the shoulders.
Remember also that a 12-lb. load for a 70-lb. child is 17% of their body weight. It's the equivalent of a 31 lb. load for a 180 lb. adult! Remember also that the adult has fully matured joints that are far less subject to stress injuries than a child's. I doubt that many 180-lb. adults can carry 31 lbs. in a frameless pack.
I'm sure that if you stripped down a Deuter Fox 30, incorporating its frame into a simple Dyneema pack bag with mesh pockets, no gewgaws, no zippers, no extra pockets and other weighty gizmos, and a little less foam padding, you would have a fully adjustable 1 1/2 pound pack that would work just as well. That would be a whole pound of saving, which would either lighten the kid's pack or allow him to carry another pound of real gear with just as much comfort.
Another possibility for older children might be the Gossamer Gear Gorilla in a small, but I'm not sure that it would work with my grandkids because of no load lifters. I may get one for the 11-year-old boy (who will have outgrown his Deuter Fox 30 by next spring) to try before giving that one up. If the Gorilla doesn't work, I don't know what we'll do. The next size up in standard youth packs weighs 3 1/2 to 4 1/2 lbs., meaning that most of the extra weight the slightly older child can carry is all expended in the pack!
I'm sure the standard manufacturers are not going to try to fill this hole. I wonder if some of the cottage manufacturers (such as Gossamer Gear, Six Moon Designs or ULA) would be willing to fill this gap with, say, an "extra small" size pack. And, in the case of GG, put load lifters on it.
I just wish I could sew!