To clarify.
Its too easy to westernise, and too easy to keep up, but we wont make a new system until we have more fun one that is still balanced.
How exactly is it too easy to keep up?
It seems like the problem is that the penalties for being in the worst tech groups are too severe to remain competitive, and therefore Westernization has to be easy, in order to allow ROTW to ever compete with Europeans, even in their own home theater. But Europeans didn't achieve absolute military supremacy until the very end of the time period, so it seems to me that it'd be better to just reduce the tech penalties for at least Asia.
But if tech disparity is reduced, then it becomes a lot easier to maintain mil tech parity, which most intelligent players can already do if they manage their points properly. So it seems to me like we need a system where ROTW will consistently tend to lag just enough behind Europe, such that the Europeans have a distinct advantage, but aren't guaranteed victory - and where a player or occasionally an AI can, if they pass a suitably difficult hurdle, manage to maintain parity.