The steel chassis provides rigidity instead of a traditional frame. They ended up having to be flat, not curved, to meet the design goal.

I guess we all just want something that “looks like a pickup”, is heavy, and guzzles $7 a gallon diesel fuel

IIHS only really tests how good a car is at preventing an accident, not what happens when it fails like for example Euro NCAP does (and so does NHTSA starting nowish).

No actually the lightning and the R1T are pretty well loved by the people who took a chance on them

I would say the issue is more that there has been little to no progress in mainstream consumer car aesthetics in the past 25 years. It used to be that you could clearly tell a 50s car from a 60s car from a 70s car from an 80s car, etc. Everything from the past 25 years or so is pretty indistinguishable, so something comes along with a clear but possibly misguided aesthetic vision, its naturally going to appeal to some people.

But where I live (deep blue territory) most people would not be caught dead driving Musk’s favorite car around

Don't speak too soon, we have a few more years to go.