In the subject of Roxie Marie... let's not forget she was one of multiple attempts to add some female diversity to the show, not to mention keep Biff on as a relevant character after Richard Hunt passed on, and left Sully. Among other things, it was really really hard TO get female characters to stick. Other than Zoe and Rosita, there haven't really been any girl characters from that era with staying power. Lulu was mainly out of the show because of the puppeteer being on Broadway with Avenue Q. So far, the only new female that has staying power is Abby, and I think she's gonna stay there for a pretty good time.