The real problem is that they seem to be going away from 3/4 ton SUVs (and there never were 1 ton SUVs, and even the 3/4 ton ones never had the suspension and payload ability of a similarly-equipped pickup). There's no reason why an SUV can't be built to be a BETTER tow vehicle than a pickup, but the fact remains that the current offerings aren't. Although I'm now a fifth wheel camper, I might change to a TT based rig if they made an SUV I thought worthy of pulling a big one.
Trailers are bigger and heavier than ever now, taking advantage of the capacity and power new tow rigs have. Unfortunately, SUVs have gone completely the other direction.
There may be legal issues here, too, since nobody has ever tried to make an SUV with a 12,000+ lb. GVWR, it's unclear what legal area it'd occupy.