[The point is that trying to recreate a model of how was ruling a Country in those years does not mean to design a complicate system. A model is in fact a simplification of the reallity, but it does not mean that we should make up our own rules. Military and dyplomacy was managed by rulers (more or less) as well as general economic decisions, but not every factor. I just mentioned trade becouse of its relevance. Governs could promote trade, but not direct it, and be more based in offert and demand and of course access to markets.
The system already present was created a few years ago and I think was really good, but maybe some aspects should work as they used to: governs could create the conditions to let something happen, but not make it happen, becouse it was someone else choice. This aspect would make the game more exiting.
New ideas or a new system should not make the game more difficult, I pointed out some ideas that will not do it, but maybe are not the best ones. There are many others that maybe after some work on them could be reflected in new games.