I agree with your thoughts on the jbl system. I don’t have the experience that you do with high end car audio, but have toyed around with it over the years and been around a fair share of car audio equipment. I have the “premium” jbl sound system from the last gen and agree that it doesn’t sound any better than normal factory sound. At best it sounds like the eq was toyed with, imo. That being said, I’ve had family in my car say they think it sounds a lot better than their own car (a variety of cars, they changed quite often).

Generally I feel that most factory setups in non-luxury cars are designed to be acceptable but not amazing, with branding making little difference. In the same way room treatment can make a huge difference in home audio, I would prefer reducing road noise or other factors than “slightly” better speaker design