That's the idea. There were more people waiting for trains inside the station than waiting in line at the metal detector. Russian officials claim that the barricades reduced casualties.
Suicide bombings in the middle east over the last 10 years, in comparison, have about a 1:3 ratio of bomber to victims. That's a mean, but the outliers tend to barely break 20. So it's difficult to believe that number was reduced by a large amount.
Yes they did, but according to this article they claim all sorts of things, much of which is not true:
http://latitude.blogs.nytimes.com/2013/12/30/powerlessness-a...
Such as the identity of the bomber (she later posted on her FB page, "Nope, I'm still alive!").
Not that I'm trying to imply that Russian officials are particularly different in this regard!