People constantly underestimate adhesives. Properly applied wood glue is stronger than the wood itself. The problem with gluing everything together is repairability.
Adhesives also allow using thinner metal for the panels, which saves weight and cost. Metal gets harder to weld when it's thin. Though newer laser welding technologies may offer some improvement.
I think the adhesives will release with heat but honestly I'm not sure how body work is done on those.
