I see no way that a designer can know what "the public" wants. How could a designer get an adequate sampling?
It seems reasonable that a designer whose talent has enabled him to create models that sold well in the past is likely to have new ideas that will also appeal to many buyers. and therefore he will deserve to be well paid. I have wondered if designers have any way of getting feedback from the car salesmen, who have contact with large numbers of buyers, and so ought be qualified to have valid opinions.

Apophasis:The rejection of several reasons why a thing should or
should not be done and affirming a single one, considered
most valid.