imo, if they already have a Mario/Luigi/Peach/whoever course in the retro cups (imo if there has to be an exception it should be Bowser and maybe Mario, as Mario Circuit and Bowser's Castle are staples of the series; even Rainbow Road could have doubles) there shouldn't then be another course for them on the equivalent of the Nitro cups in this game. It takes up space for better, original tracks when the ones from the previous games work just as well.