You know what? This is an excellent question. Why don't cars look sexier? You make an excellent point that, in the days of 3D printing and lightweight materials, there is no reason at all that fantastic designs aren't achievable.
Here's to hoping that at least one of these manufacturers gets the message. I'd even be satisfied with a return to an older sensibility for auto manufacturing, something like what was done with the Dodge Challenger and what is being done with the Ford Bronco.
Any escape from the current bland copy and paste banality of modern car design would be welcomed.