The assumption (and it seems like a fair one) that sub-classes can't 'take away' features from the base class really seems to get in the way of making a new or existing sub-class work. Whether you need to take away features to 'make room' for something else, or because they're inappropriate to the concept.
Alternate Rages for Barbarian sub-classes could get you the 4e PH2 Barbarian with it's crazy-magical '____ Rage' invokations, and, with a more defensive/defender & shape-changing 'Rage' a Warden, and maybe the odd Frenzied Berserker or Battlerager, as well...