Victoria 3

[The Minsky Moment]

I feel they could try to make specialized economies more feasible. As is, often the optimal way to play is aiming for autarchy. It would be neat if international division of labor was more of a thing, or investors would see the potential of producing for export.

Generalist Gamer just released a Youtube video that goes into detail on this very subject.
https://www.youtube.com/watch?v=r5CWaVKLAoE

It's definitely an issue: during the timeline covered by the game, the share of GDP accounted for by international trade rose from 5 to 15%.  That isn't being simulated at all by the game.

The advantages given to overland trade routes are basically backwards; even in the age of rail, sea was and still is almost always more efficient. Same with how MAPI is implemented - the impact is spread evenly across a country, except if there is special river access.  In reality, coastal areas with ports were strongly tied to market whereas interior areas were not unless they had unusually good transport connections. Coastal areas in different countries should often trade more easily with each other than with interior areas in their own country.

As an example - see this map of British coal trade in 1864. https://www.loc.gov/resource/g3201h.ct007672/?r=-0.016,-0.155,1.111,0.818,0

Most of the British coal exports went to western Europe, with leading recipients including France, the Netherlands, Belgium, German states (the "Hanseatic" cities), and northern Italy.  Many of these countries had substantial coal deposits of their own or could access it overland within country or custom union. But for example in France, coal production was concentrated at this time in the Loire basin, in the west and south of the country.  Iron production was in the east and north.  It appears in some cases it was more efficient to import coal by sea from Britain through Dunkirk than to shlep it overland. 

Another significant recipient of British coal was the Russian fleet at Kronstadt, it was far easier to get coal shipped from British ports then from the Russian interior.

Vic 3 as currently set up doesn't replicate this kind of trading pattern.  Improvement of shipping tech allows you to change PMs to produce more convoys but what it really should do is decrease transport costs for goods.  There really should be a kind of "race" between transport cost improvements between shipping on the one hand, and rail/canal on the other, with shipping almost always ahead for areas around or near big ports.  if this were done properly it would also create a more meaningful distinction between free trade and protectionist laws.