Most aircraft these days are being made of fiberglass, aramid fibers, and carbon fiber. Yes there are still some being made of aluminum, but the trend is going away from it. The techniques and glues being used to laminate RV walls have been improved a lot but as said before... not all fiberglass is fiberglass as we might know it from boats and other stuff... and where luan is used, you have to keep the water out. If it gets wet, the luan plywood layers separate and delamination is the result.
The aluminum framed, foam filled walls consist of an outer, very thin layer of some form of glass matting that was laminated to luan, with the outside finish already applied. That gets bonded to the aluminum frame, foam block insulation, and another sheet of luan with the inner finish applied already. They bond this with a polyurethane glue and use either a roller system or vacuum pressure (my preference), and heat. In my opinion, this makes a much stronger and lighter structure than the stick and tin of yesteryear...
Aluminum skins could be pop-riveted to aluminum framing, but the amount of framing needed would be very expensive... Couple that with the fact that this is very labor-intensive, and the cost jumps way up there.
J & D in Lovely Weatherford, TX
2016 Jayco White Hawk 28DSBH TT
2014 Ram 2500 Crew Cab 4X4 6.7L Cummins