I think that the RV industry is a "bleeding edge" consumer of new building technologies. In some cases it causes unwitting buyers of this technology to suffer, like the early ultralights. OSB is a good example of a nice idea that needed maturity. Plywood is a very mature product and most of the kinks have been worked out. However, it is heavy and has structural limits. Plywood's ability to avoid warping and delaminating when wet depends on the cement between plys. Surface treatment is also critical since water can infiltrate through the top or bottom ply.
OSB on the other hand, has the "glue" as part of the structure itself. Unlike plywood, OSB is almost a casting...resin permeates everything. If the resin is not waterproof, then the OSB could literally dissolve. If the resin is water and mold resistant, then the OSB becomes an almost monolithic construction material. Laminated walls, floor, and roof actually make a lot of sense. Our camper has luan, foam, and aluminum sandwich walls, floors, and roof. I weigh 250 lbs and I can't make the floor flex at all. Even the slides, which have OSB over aluminum floors exhibit excellent rigidity.
You do get what you pay for. A cheap ultralight may indeed scrimp on materials and cut closer to the bone on structural parts. I get the feeling that while build quality is still deplorable, the engineering in even economy trailers has improved. Part of the reason is that we buyers can talk to each other on forums like this one. The word spreads quickly when a company makes junk.
