Shipping + new packaging + vendors producing at much smaller scale are all negative environmental factors.
I don't think they need to include one in every box but including half of the fast charging components is ridiculous. Either include a charger + cable or don't include either and offer a way for people that need those components to buy them alongside the iPhone.
If they really want this to be about the environment they could easily offer a 1:1 exchange/recycling for old USB-A bricks for USB-C bricks. Maybe only 1:1 if it is alongside a purchase of new iPhone. Otherwise $10 credit with trade in of Apple USB-A brick.
The whole thing is just obnoxious greenwashing, IMO.