"he's the bad guy...because he's British"
To pick just two examples, Die Hard and The Avengers would both have been considerably less interesting if the bad guys were re-cast. To pick another two: Superman 2 and Beverly Hills Cop.
The British get the bad guy roles in Hollywood films because a) the British are the traditional enemy of the Americans (the War of Independence* was a pretty big deal) and b) British actors are better, whether they be giving a finely nuanced performance, heavy with pathos, or just chewing up the scenery at every available opportunity.
As much as I enjoyed the last Star Trek film, it's Cumberpatch that I'm most looking forward to watching, in this one.
*Not sure why they hate the French so much, though.