But that's the whole point. You'll buy one at that point because you need it. Giving people the brick whether they need it or not is what makes it wasteful and costly for all involved.
The point is that you will most likely immediately need it. Example, I charge my phone bedside. Now I need to either buy a brick or if I do what Apple wants me to do which is to buy the MagSafe charger.
This incentivizes people to buy yet another Apple accessory. That and margins are the real purpose. One more foot into the Apple ecosystem.
What is that based on? The vast majority of iPhone buyers are existing iPhone users and will not need the brick. I have 4 bricks and cables in a drawer right now and I don't need them at all because I have a Qi wireless charger on my nightstand.