How is this any different from any other high demand product?
In many similar situations people don't have reservations. Guaranteeing they receive a product requires them to be one of the first people through the door when the store opens. Taking reservations may have created the false impression that one could show up later in the day without the need to wait in a long line. The other difference I can think of is that in similar situations the manufacturer and the retailer are…
I concur with you in everything you said, but I think it is important to remember that that impression was false only because Apple arranged it that way deliberately.
As others have stated, they knew the maximum number they could serve in a day and could have refused to reserve more than that, or made reservations for specific times of day and then ensured they had enough staff to cover those reservations.
If they truly got overwhelmed by surprise (say some employees got sick), they could have started handing out numbers so people could be free to walk away for a bit and return closer to time based on their number. Etc.