Vehicle "platforms" cost tens-to-hundreds of millions of dollars to develop - I'm not sure if you're aware of that. Every Acura, Infiniti, Lexus, Lincoln, Audi, Cadillac and Chrysler will forever share a platform with lesser vehicles. It allows you and I to have luxury at the prices you see today - if the RX was a standalone it would cost, well, what a Bentley or Maybach costs.