The US has a tendency to export its bad ideas along with its good ones, so readers elsewhere might still have reason to be concerned about what happens there. These weapons are already used by some police in other places, like in Canada where a protesting student was seriously injured [1]. French police used flash bangs in the recent hostage situation in a grocery store [2].
[1]: http://rabble.ca/news/2012/03/police-violence-rise-montreal
[2]: http://www.theguardian.com/world/live/2015/jan/09/charlie-he...