So you are saying other Civ games have even worse UI than Civ4 without mods?
Yes. While none of these are too bad with misinformation compared to other strategy games, they all have at least some misinformation. Civ 4 is miles better than 5 or 6 in terms of input efficiency. 4 can copy/paste queues, queue up multiple cities simultaneously (with a variety of ways to select them), add something to queue with 2 inputs, waypoint, manage cities from the sortable list of cities (including switching builds after sorting by production etc), and isn't so trivial to out-input unit movements faster than the game can keep up on > recommended specs.
5 and 6 don't have these things. It is much slower to play turns and manage 15-20 cities in Civ 6 than managing 50+ would be in Civ 4.
It's truly amazing that Civ5 and Civ6 have worse UIs than Civ4. I mean, shouldn't people learn from what went on before them?
People should learn, and a lot of game developers do learn. Despite that, there are UI conventions from Warlords 2/3 in the early-mid 1990s that should never have disappeared from turn-based strategy, but somehow did.
UI is uniquely bad in strategy games (at least, ones I've played), I think it's one of those things where they just don't tend to invest properly in it in this game genre, despite the complexity needing more rather than less investment. UI isn't a "lost art", if you look at gaming as a whole there are games with good-to-excellent UIs (in terms of information presentation/clarity, number of inputs required to do things) that have released every year from early 1990 until now.
If Civ 6 put even half of the time/budget used for its art/character animations/speech we would probably see some decent practices that others have used for 10-20+ years make it into the game.
In a way, some things don't change though I guess. While there are examples of excellent controls/UI dating back to the 90s, there has also always been volumes of games with bizarre choices or poor controls alongside them. Maybe there just aren't enough people who are good, or even adequate, at it to go around. Still, while the appearance of the game is important...it's kind of wild that art director would be emphasized more so than the person who dictates how players interact with/play the game. I would expect them to at least see equal emphasis (or I would if I didn't have a ton of past observations which did otherwise). Civ 6 appears go have put some care into how the game looks at a glance for players, but minimal if any on economizing inputs for players or managing how long players are making decisions vs interacting with UI/fighting it to act on those decisions.
I've seen people blame mobile device accessibility etc on this, but in the current era of making hotkeys bindable and allowing shortcuts, it seems like input efficiency should be at an all time high, not something that's notably declined in a series across a 10+ year period.