Writing rules and balancing is a learning process. Its also a steady process where you have to actively listen, play, adapt and rethink.
We have the means for a living rulebook and living codices.
GW is not interested. They plan their books according to marketing stategies and have a tendency to break their own ruleset at a certain point which makes older codices (who obey said ruleset) less fun and more binary.
You maybe want to listen to this:
[url]https://www.youtube.com/watch?v=e31OSVZF77w&list=TL9eBelUEBkDUnoo6c127TYyk uML9SBDMB[/url]
[url]https://www.youtube.com/watch?v=Bxszx60ZwGw&list=TLQVdvgb_uk8iugfn0nY_SrdA wPgRtz7N5[/url]
to get a better idea of game design