I think you have a point: it appears that
Madison and
Kennedy in particular started growing in popularity for reasons other than presidential association -
Splash for
Madison and the MTV personality
Kennedy for
Kennedy.
(Though I have to imagine that part of why
Kennedy adopted that as her moniker was at least somewhat politically motivated. She was an MTV personality first and foremost for much of her career, but one who was unapologetic about her politics - she rather famously chanted "
Nixon now!" at MTV's 1993 inaugural ball whenever the Clintons were onstage, and the image of a person named
Kennedy chanting "
Nixon now!" while one of the lawyers who worked on
Nixon's impeachment is onstage is really almost aggressive with the symbolism.
Kennedy is her middle name, I believe, so it didn't come out of nowhere, but still.)
I don't know that the same is true for
Reagan, though.
Andrew
put a smile on your face - make the world a better place (: