This really depends on the NRP.
Myself, I think that lots of fluff CAN be a good thing for an NRP, especially a fantasy one, since it helps you think about the different things that make your nation distinct. Hell, in this one RP I've been participating in, States of Evolution, we spent two whole pages of the IC basically working together to craft a history of the world. We've also detailed stuff about our different species, different religions, etc. It's a ton of work, but it's a ton of fun, too.
However, not everyone goes into an RP wanting to write a ton of stuff JUST to get started on actually playing the game, so there's that.
The scope of the RP is important, too, both in time and scale. An NRP can be about warring tribes, or it can take place over the course of only a few years. In such a case, more emphasis on individual characters may help.
And then there are cooperative NRPs and pseudo-cooperative NRPs where you all play as a member of the same state. I can think of two NRPs that are currently running that fit this: The State and my roleplay, Masters of the Hidden Valley. In such a case, the GM makes the nation (or guides the process of its creation) while the players play members of it that can influence its fate. In such a situation, you need character biographies, not nation sheets.
Hopefully this helps.