I'm guessing it's a big sacrifice for daily driving to carry around something people will only really need a handful of times, other than maybe a few people that live in an incredibly remote area or head to some extremely remote destinations.
Like I just said on my post, i went from almost 0 sea level LA, up to a trailhead 250 miles away at 10k feet elevation with my Solterra that has famously low 239 mile range. The area in between is mostly empty desert. You'd need to do something like that, but also do a long off road adventure after on top of it to really need serious range extension. I parked at the trailhead with 50% of my battery, left it in 20 degree overnight temps for 5 days, came back and it was same 50%.
I know people do stuff like that with Wranglers especially, but it's really an incredibly niche thing. If it's about towing I can't pretend to know about that, but that's probably another aspect. Towing is probably more common than people who do true off road adventure.
It's not cheap but I imagine improving the 410 mile extended range Rivian is what will happen vs all of these hauling around a generator.