" I just think that an American (or perhaps a citizen of another country) would be less-worried about the curtain and more concerned about his or her safety... pero c'est la vie..."

Because no other country has ever had terrorism threats?

If the leaving of curtains open was a great actual security improvement measure rather than a highly visible change of practice, then other airlines would be likely to do the same, I would suggest. I haven't come across this being implemented on other carriers I have used

Dave