Interesting theory.
A lot of people actually dislike the fact that Japan does the distribution like that.
The reason being that if you can't make a specific event, go to a certain store, buy x number of merchandise or y price of sales, you don't get that promo(s).
eg) For the newest Pitch's Pikachu you need to be a kid to receive this promo. It is a sort of [DEL]discrimination[/DEL] (I'm not a huge fan of that word in this case) against the older collectors who obviously won't be part of a children's league for soccer. More like a disadvantage.
eg) For the newest Darkrai promo, you need to go to the Pokemon Center on April 19th, and spend around 800 JPY on cards/card-related merchandise to receive that promo.
Now in Japan, it might be easy to go to a Pokemon Center, since they are so bountiful, and even if you don't have one in your city, they are not that far, only a train ride away. Whereas if they had a promo here in North America for instance and you were only able to receive them at Toys R Us, Target etc, the majority of people would be able to receive them but not everyone...
However, that being said there will always be promos that not everyone will be able to get, but I feel as though they try and make our system here more fair, so that the majority you can get without having to go on specific days, or spending x amount of money.