But according to all the people for this feature, only one or two npcs die at a time. So why can't there be repopulation again?
one or two npcs dead does not a ghost town make

I think you are just trolling now because if you actually read some of these posts you would know it is nearly impossible to save NPC's when you don't know what direction the attacks are coming from.
you are quite right on both accounts. though at times you have to see the similarities between what is going on in the game and what is going on in the forums.
when people talked about adding a point re-allocation system they where flamed to hell pretty much. basically for something they wanted implemented.
now people are upset because vampires are killing the citizens of their towns and they feel the towns will become ghost towns, which in all likelihood will not be true. their will always be several un-killable npc's(mainly children but still).
of course I do not want people to suffer in a game or constantly have to re-role characters(which was a solution forums goers offered to those who wanted a point re-allocation system. funny when the shoes on the other foot?)
I would prefer an option in the settings menu that had a slide bar which said "less vampires [.................................................V.]more vampires or a NPC repopulation system, or the ability to buy businesses and hire npcs(or force those that yield to you to become servants).
so many problems so little time however. onward to vampire slaying.