Might this also be an attempt to give hobby stores an edge over bulk e-tailers who undercut prices? There's little financial incentive to buy from a hobby store when you can get a booster box online for $85. Giving the brick and mortar stores a week of exclusivity should help them gain a niche.
It's likely that was taken into consideration as well. I'll admit, while I do support my local store a lot (I'm there once a week and always buying crap haha), if I can get a sealed product for £10 cheaper online, then I'll do that 'cause at the end of the day it's not a cheap hobby (I collect as well as play), so I make savings where I can.
BUT if my local store were allowed to sell them before official release then I'd likely buy from them instead of online because impatience

I say
would because...
Us Brits always have to wait
Yep, pretty much what I was here to say. My local store does fantastically well for itself, particularly surrounding pre-releases (largest SM pre-release in the entire world iirc

), but it would be awesome if they could get the new cards before the bigger retailers like Toys R Us and the supermarkets. Really hope this is implemented for the UK (and well everywhere, I guess) in the future.