That negates the purpose of a pre-order system. As someone who preordered the iPhone, it was extremely frustrating to see that people were able to walk into stores and pick one up during the weeks that I was waiting. Why even bother preordering if you don't have priority access to the device over those that didn't? It's not a "send me one after the stores have been stocked" system. I'm going to be an extremely upset customer if Apple goes back on what it has publicly stated and offers my model watch in the store before I receive mine.
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Because not selling a product is how you make money.