Roth was no doubt a genius. More than that, he was relentless. He became very commercial. You can see the same thing that happened to Elvis happening in Roth's career as promoters and publishers got hold of his work. Not that he wasn't a promoter in his own right.
I see a lot of his influence still today. The ads for the Pomona Swap Meet are in Roth's art work style.
The comparisons of his work to today's products missed, IMHO.
The Rat Fink was never animated that I know of and I didn't care for the interpretation. However, someone spent a lot of time documenting Big Daddy's early life. Read Wiki, he became a Mormon in 1974 and lived in Utah during his later years. That doesn't make too good of a movie script.
I think the movie "American Graffiti" reignited the early days of hot rods for many. It never really died, but almost.