I have to disagree with you. That's the launch day weekend game. Some people wait in lines, for the fun of it, or because they want to pay cash, or whatever the reason and some people pre-order, mostly in the hopes of avoiding all the lines and waiting and not being sure if after all that they will get the color and storage (and now size) configuration that they want.
But Apple has historically set it up this way. You can pre-order or wait. If they filled all pre-orders first, then by next Friday there would be nothing left in the supply channels for any sort of launch day and the people who want to wait in line would cry about being forced to pre-order or wait. So they split it up, though I would have to think it is skewed towards the pre-orders. And the carriers do this to. It is good for foot traffic and publicity but there is also something logistically sound about getting stock out through pre-orders to mitigate some of that foot traffic and to deliver product to people who don't have Apple or carrier stores as easily accessible.
You can cancel your pre-order if you are dissatisfied with the wait and join the launch day crowds and try that route. But you can't have it both ways. If you don't cancel your pre-order you won't have eligibility on launch day.