Nationhood has proven useful once or twice when I've enabled Raging Barbs and Barb world in the same game.
Getting instant units for one pop point certainly seems that it would have it's place (or is it 2 pop points....like I said, I've only drafted units once or twice, but if I wouldn't have been able to, I would have surely lost those particular games).
As for city states, it comes really early, usually when I only have 2 cities. If I do take it early, it's more for the +5% commerce than anything else.