It would be way more disruptive than the current system. You'll get more stories about companies laying off IT workers for cheaper immigrants, like at Disney (who recanted after public backlash).

Maybe your employer values you, but I'm guessing someone can do your job for less, especially if there is a H1B visa value added to it.

The whole problem is that H1B shops are gaming the system, and with a national auction, it gives them more leeway to game it further.