Strategus needs to:
1) Make being an average player more interesting than recruiting troops or selling goods. One solution is making a cap (defined by something) to troops led by one player. If a faction starts a serious military campaign, majority of it's members should be moving with the army on the map.
2) Make having many people trade / craft in a fief benefit the fief owner enough to let people do that. I know Strategus isn't supposed to be 100% historical simulator, but it's a general real world principle that free trade makes communities prosperous, especially compared to very limited trade. There should probably be some sort of an infrastructure variable for fiefs, basically meaning that if infrastructure is low, less people can craft efficiently there. Basically this'd mean that high value goods and low infrastructure may temporarily make it worth it to have mercantilistic trade policies, but in the long run allowing people to trade should be worth it. But really, whatever is implemented what matters is that people should keep their fiefs open to non-bandit visitors in general and not because of game forcing it, but because of it being worth it financially.
3) Equipment prices. Yeah. They should be lower compared to gold income.
In general for Strategus economy I'd like to see ability to invest in things. After all, in real life there were three ways to be rich back then: Prosperous business, having rights of taxation or inheriting money. First two suit Strategus, but in Strategus you can really currently earn only with the first and it's implementation is a bit one sided too. It'd be nice if the player could increase crafting efficiency and speed by investing money on a fief. These would obviously be always revokable (or burnable if that's better for game balance) by fief owner so it's a risky investment, but if work and trade in a fief brought prosperity in form of taxes to the fief owner too, there's no real reason to burn/revoke the investments of people randomly.
Basically it's nice to see Strategus as more than a map where people can fight, but sadly the current implementation for economy is very simple, boring and also punitive for people who aren't friendly with a clan owning fiefs.
But yeah, these aren't really short term suggestions obviously