Kurt went from one of the most hated drivers back in the day, to becoming one of the most loved drivers by the time he was done.
Those years of driving for really shit teams I think is part of what helped him become less of a hot head, and gain fan support. He realized that just because he has talent, doesn't mean he can act like an asshole and still be able to be in top rides. So he made improvements to better himself, and fans noticed that. It's what turned me into a fan. As you both said, it really sucks he can't go out on his own terms.