How about specific quest lines for each race. The quest line could/should highlight the good aspects of that race (they've all done terrible things), and at the completion of the quest line a new CP tree opens up. This new tree would allow you to 'assume' the passives of any other race through CP points, but, once a single CP point has been attributed to that tree, it disables the passives of your current race. This would allow you to get the benefits of any race, played by any race. It would open up a lot in RP and personal preference. I would like to play as an Orc or Redguard mage, or a Breton nightblade. It stinks to be 'locked' into certain races if you want to get the most out of a particular build.