Apple probably would allow it now (maybe even previously), it's most likely the licensing price which they want to levy against third parties that makes it not cost effective decision immediately.
Don't see them including a power brick in the box for two reasons;
- they are obsessed with things being minimalist (take their quest of thinness over function as many see it). I think sometimes they plan what to include with a phone based on the box design they can come up with
- including it with the phone will reduce the amount of profit they can make from a separate item, as they will have to factor in the brick with the phone price. Keep the phone cost the same and sell the brick separate (or allow Apple ecosystem users to use Macbook bricks) sidesteps so people think they are getting better hardware for the same price, with most often overlooking the need for the wall charger which you have to buy later for $79 etc
Apple are coming almost full circle by charging for extras and making items not upgraded-able or user repairable (Apple of the 80's)