Anyone reading some of the comments on the Star Wars trailer would have been pretty shocked to read allusions to riots in Ferguson and fried chicken.. (I spotted them first - depressingly - on the ailing aintitcoolnews)
In response to that this is a good article - Of Course There Are Black Stormtroopers in Star Wars
It alludes to one slightly overlooked stereotype in Star Wars -
"Everyone we meet in the Imperial officer corps, for example—the chain of commanders that Darth Vader is always Force-choking out—is white (and seemingly British)."
So having established the Imperial officer class is British the VII trailer reveals that at least one of the Stormtroopers is as well. Aside from the race thing... and lets not forget Chiwetel Ejiofor as a posh British Imperial officer in Joss Whedon's "Serenity"... it is entirely consistent.
Most obvious Imperial villainy in movies for last 40 years has had a a massive Union Jack on it all the way through and there has never been a peep about it over here (Nothing like say, The Patriot).
Nearly 20 years after we handed Hong Kong back - it's just nice to be noticed.
In all seriousness if Max Von Sydow (Swedish) turns out to be an Imperial officer this is obviously further dispersing the racial/national stereotypes set previously. It's almost as if someone has given this some thought.
If you look at the the back of the suit incidentally- I think Boyega is a TIE pilot, probably shot down in battle with the Falcon in the trailer. So look out for more fuss when it turns out the black guy is more than just a grunt.
And one more shout out for Attack The Block. It is kind of like watching the original version of The Blob with Steve McQueen, it's an ingenious, fresh, fun movie lit up by a star obviously on the way to bigger things.