Well, I don't know the layout of the stations, nor do I have any real knowledge of explosives, so I can't really comment on if they actually helped (more than any normal wall or objects in a room), but if you look at the numbers, 14 and 17 fatalities (with about three times that injured) is near the high end of suicide bombings where the bomb is carried on a person.
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.