I'm kind of curious about trade in particular, because it seems to come up in threads for this game a lot and the consensus seems to be to keep it as is but automate as much as possible (or at least not break existing trade routes so often).
Why? Not why it should be automated (if it's like EU: Rome, it's a micro mess), but why bother having a trading system at all, or at least one that the player needs to directly control?
You get the ability to get more money than if the AI handled it off screen, I guess, but players are swimming in money anyways in every single Paradox game, because that's how the game progression works.
You can also stack bonuses/modifiers/enable troop types, but the first 2 are also something that there's way too much of in every Paradox game, and the 3rd really should be locked behind something else.
So why have a hands on trade system with these resources? From Paradox's point of view, it's a great time sink to keep you clicking and doing something in the game to get your payoff, but from your player's perspective, what's the point besides getting the payoff?
How would it take away from the game if it was something that you could look up if interested and indirectly influence like in Total War games (I blockade this province/exports halted/enemy loses money/resources) but otherwise you set something like a trading tax that increased or decreased your overall trade income, or any kind of system that didn't have you setting up individual trade goods with individual provinces?
I have come to the conclusion that some things in I:R were designed or work best for MP.
For example, in a SP game trade routes break whenever there is a war and the country where the trade originated controls no more the trade good surplus. For me, this helps the player to be aware about commercial partners wars but I understand it can be tedious to reestablish all the trade routes every time.
In a MP game, you will establish your trade routes with your allies. Having strong commercial allies can be very powerful in MP. Trade routes do not break as often as in SP and you take more care to not import trade goods from your potential enemies. First, because you will loose them when anyone declares war to the other and second because you are helping their economy.
Also, in a competitive MP game you cannot get enough money to pay for your mercs, legions, navies, buildings, etc.. and trade is maximized by
- building forges, founding cities, etc.. to have more surplus trade goods to export
- building academies, roads, and marketplaces to increase trade routes
Trade routes also allow to import the goods necessary to build stronger ships (wood), units (iron, horses, steppe horses, camels or elephants), military bonuses, happiness.. etc..
All of these steps help differentiate the good, the bad and the ugly player. If you get rid of trade, you are also making the game less interesting.
These nuances are lost in the SP experience, as you do not have to do much to beat the AI. One example is naval battles. In SP you can beat the AI by building a lot of liburnian ships. However, do not try to compete with another player that has built level three ports, imported or produced wood in those provinces and built Hexeres with the national +10% damage for navies bonus by importing two hemp in the capital province, you won't cut it.