Fundamental Flaw of Civilization 5 & 6
My insight on why Civ 5 & 6 are boring and shallow games as first posted on Civ Fanatics.
These arguments about units per tile really miss the real fundamental flaw with Civ 5 and 6: lack of city micromanagement. Once they removed attention from the cities, all you're left with is unit simulator. That would exacerbate any unit/tile system flaws.
In older games, including 1-4 and Civ Rev, I would give so much care and attention to my cities. Every turn I would fret if they have enough yields and the right amount. Whether I should have extra food or extra production. This seemingly minute dilemma made a huge impact on how much I care about my cities and my civ.
Unfortunately, they essentially removed all city management from 5 and 6. So that I no longer care about my cities, what their output is, what tiles surround them, etc. I used to spend over half the turn in the city screen in older games; now they're just bothersome reminders. I just don't feel the connections with my cities anymore. They've become sideshows to the tedious shuffling of units. 99.99% of the turn is wasted shuffling units like they're so fragile and be stepped over.
Meanwhile, maybe one second per turn total at most is thinking about my cities. Really, 99.99% of the time they might as well not be there. All this hoopla about happiness and housing is better whatnot, doesn't matter. Because you'll never spend time looking inside your city. Looking after the citizens, how and what they're doing, if they're behind in food or production or trade. That doesn't happen any more because they've simplified and streamlined too much of city management.
So the real question is 'Why did they make cities the background, where they used to be the focus of the game?'
In previous games, you treated cities like they were your children, babies. You meticulously cared for them, tended, checked in every turn to see how they're doing. They showed icons of the population and makes them more relatable. Food and production progress were front and center to show you their growth.
5 & 6 removed all these human factors. Now they're just cogs in the 'tactical' war machine. You spend maybe a few seconds every 10 turns thinking about cities, when the interface pops up to change their production. Districts only happen scarcely. Sure you have some decision making with districts, but that's one-time thing per district.
Tiles and yields also feel less important. For one, there's too many types of yields, so that dilutes the value of each. Second, the interface is set up that you have to squint to know that those yields are there. That makes them feel less important, thus you tend to put less focus on city output.
In short, much less focus on cities, so what else is there to do? Nothing except uselessly, tediously shuffle units around. In the past, I spent over half the time in the city screen. Now I don't even check in at all until they pester you with pop ups, since you can't end the turn with empty production.