Well there was John Waters' film Hairspray, then John Waters' Broadway musical version of the film, then the film version of the Broadway musical version of the film, then the live TV musical version of the Broadway musical version of the film -- audiences did not seem to get confused and each production seemed to meet with success. And Mel Brooks did a similar repackaging with The Producers and Disney did the same with The Lion King.
It just seems odd that so many recent(ish) Broadway musical successes have had movie versions made -- Rent, Les Miz, Dreamgirls, Mama Mia, Sweeney Todd, Into The Woods, Evita, Jersey Boys, -- all except this one. I honestly don't know if the decision not to make that movie was Hollywood's or Mr. Herman's.