Very true, that in the most ancient times nobody built on the coast: nobody had the technology to exploit the sea until efficient sails were developed and applied. But that took place well before the Classical Era (Bronze Age sailing vessels were traversing the Mediterranean and Black Seas by 2000 BCE, possibly earlier) and after that, the sea was the preferred highway for trade, and that and rivers were the only way to feed a really big city: Babylon and Antioch on rivers, Rome, Alexandria, Athens, Syracuse, Carthage, Tyre, Byzantium - all on the coast or up a short river/portage like Rome and Athens. The Romans built 1500 ton capacity grain freighters to run grain from North Africa to Rome, the biggest ships seen anywhere until the medieval Chinese ocean-going 'Junks'.
So, the fact remains, for most of the game, the sea should be a lot more important than it is now.
Exactly !!!
Just look at this article:
https://en.wikipedia.org/wiki/Landlocked_country
"As a rule, being landlocked creates political and economic handicaps that access to the high seas avoids. For this reason, states large and small across history have striven to gain access to open waters, even at great expense in wealth, bloodshed, and political capital"
"Historically, being landlocked has been disadvantageous to a country's development. It cuts a nation off from important sea resources such as fishing, and impedes or prevents direct access to seaborne trade, a crucial component of economic and social advance. As such, coastal regions tended to be wealthier and more heavily populated than inland ones. Paul Collier in his book The Bottom Billion argues that being landlocked in a poor geographic neighborhood is one of four major development "traps" by which a country can be held back."
Note that the article is mostly about the current situation - it was even truer before railroads, trucks on paved roads and international trade regulations.
Here is a very detailed world population density map:
http://luminocity3d.org/WorldPopDen/#3/35.96/-0.26
Note the concentration of people along the American, Australian and east Asian coast.
Europe, India and China are a bit of an exception due to extremely high population density, millennia of development, political unity without trade barriers, and fertile, navigable river valleys (Rhine, Danube, Ganges, Yangtze,...)
About solutions:
The "production from population" mod (available in the workshop, created by p0kiehl based on an idea from Youtuber PotatoMcWhiskey) helps alleviate the issue in a fascinating way.
- population provides base production (similar to science and culture) with a bonus for tall cities
- mines are no longer buildable on all hills, only on ressources (optional part of the mod)
- coastal cities get a natural, immersive production boost this way
- The most valuable areas are no longer in hills but along fertile river valleys
I personally added a small bit of extra gold/food to coast tiles and farms give 1 full housing, further improving the immersiveness.
