Wow, Callan, a bit bitter, are we? (and i can understand that, to a degree...so that statement is not meant as a provocation, just so we are clear

)
I'm a roleplayer of many years myself, and am also reading up on game design, at least a bit. I'm no big fan of all the Game-Theories like GNS and that stuff because in the end, i think it is just babble. Every game group has a different vibe and enjoys different parts of the game. So it will be impossible to generate The One True RPG anyway.
Therefore i don't think we need to narrowly focus our game. What i want to try is 1) to put together the most important world-bits and 2) finding and moderatly adapting a rulesset to the flavour of Earwa (or at least what
our consensus will be on what the flavour is). That last part might lead us to focus, in the wider sense of the word. But i think it would be a shame to say "Ok, let us make a game that only tries to let players play Mandate Schoolmen". Eventhough for some that might be what they are after in a PoN RPG, i think it is a way too narrow focus because you can be sure that if you have a group of 5 people (and we will even assume here that all of them read the whole of PoN), not all of them like the same things about the books.
What the rules should provide in my opinion:
- A way to simulate reality (to whatever degree seems appropriate)
- how the cultures and upbringing (caste, career etc) factors into the characters capabilities
- how all the supernatural stuff "works"
In every other aspect, the rules should take a backseat to whatever is happening at the game table. Rules are guidelines, not laws. And they should never dictate the game/story flow (which a lot of the new indie-games try to do, which can lead to interesting results, but is most often a imagination-stifling corset *).
* at least for my taste/way of gameing