Well, the dealer relationship IS worth something, as far as I'm concerned.
This cannot be installed aftermarket easily, at least not as nice as the factory setup in which you have pleasant lighted buttons for both passengers.
If you've never lived with it, then maybe you won't miss what you've never had. On the other hand if you plan on keeping the car for 10 years then you should get it the way you want it. Perhaps offering the dealer marginally more profit for the THIRD re-order will make it a win-win.
Or, you can just be completely ruthless and walk away and order from another dealer.