Even with a full frame vehicle the body adds rigidity against torsional twisting. The last glue job I fixed was a Suburban that had a roof put on at another shop for hail damage and it was leaking water. The front edge of the roof was partially separated under the urethane set windshield and I found a few places down the sides where an epoxy type seam sealer had cracked. I'm not really sold on the epoxy seam sealers either. They're fast to cure and you can paint over them in no time, but seem a bit brittle to me. I've had to re-do a few bedsides where I had done the job. When the stuff first came out everybody used the glue and then the comebacks start coming including ones that have been hit a second time after being glued together. The 4 tacks or plugs on the corners they recommend just isn't enough.