The game has definitely been improving a lot since release but there is still one thing that really bugs me. I understand that a lot of people talk about an "Information" age after "Modern", and that's pretty much teased and confirmed at this point (which is great!) BUT to me the one that feels the most lacking, since release, is a proper medieval age or - to be more historically neutral - a "post-classical" age.
I personally feel like the transition from Exploration to Modern works decently, you end Exploration with gunpowder units and such and you start modern at the height of napoleonic warfare, line infantry and knocking on the door of industrialization. That works. Might not be perfect, but works.
However, Antiquity > Exploration always felt really abrupt and awkward to me. Many games later I still feel like it's definitely the most jarring transition in the game, we're basically going from the consolidation of the old world empires (Romans, greeks, egyptians, etc.) to the rush of the Age of Discovery and Age of Sail, effectively skipping a thousand years of dynamic history in-between. We're going from "We've built the 7 wonders of the ancient world!" to "I must secure spice from the distant lands!". That feels very, very odd.
And personally I feel like this is actually the biggest hurdle about the so controversial Exploration Economic legacy path; I quite like it, I think it's a great idea, I just feel like its placement in the game is the reason it has given so much trouble. It starts awkwardly early, because (IMO) we're squishying 1000 years of history/Medieval age in a few turns of the early Exploration Age.
So yes, in my opinion a "Post-classical" Age is the age that is missing the most from the game right now. It could be all about the consolidation of the continental powers estabilished in the Antiquity. If the Antiquity was all about exploring your continent and estabilishing your empire, the...