Well, the reverse GJ-bu scenario would be like an Otome game, only with an extra-spineless, Super Beta Otome Protagonist. At which point, there'd be accusation that she's a chauvinistic portrayal of woman.
More seriously speaking, I really think Harem leads should design their characters with a more Shojouish slant, by first taking an acceptably strong Otome or Shoujo lead (the kind that are in the vogue today) and then extracting those characterizations and adjusting it for a generic male. at which point, the male would stop being generic... and
Well, to be honest, do shows with Generic Male Protagonist actually become big hits? I'm getting the impression that there are many badly selling animes with very generic, passive male Protagonists, so I wonder whether the argument: Producers keep portraying such protagonist because they sell to the Otaku crowd is really all that valid, once you actually look at sales and popularity.