I agree. It's also a good way to control scalpers by limit how many one can purchase.
Apple is making the process more civilized. Instead of 200 people lining up around the block at the Apple Store, there is an invisible line that guarantees everyone in that line will have one. No riots, no stabbing, hopefully no thieves, no fingers getting pulled off, or god forbid, a severed hand while someone was wearing one.
https://www.youtube.com/watch?v=HnQEZ5MLxGs&spfreload=10
You already know the requirements, why not preorder it? Instead of waiting in line for hours or days, just go about your life until the store opens up and you can just walk in and walk out, no waiting, no hassle.
Eventually, when the initial demands are gone and more supply are readily available, then walk-ins will take place, just like any other product.