First one: Where can you see if you have a duplicate copy and that it is yours versus one for which you have traded or are getting from a CS? That can make a difference. Unless that was patched, I only see that ability in CQUI.
EDIT: Again, just because you may not use the feature doesn't mean it shouldn't be there. There are plenty of features I haven't used through the years in Civ, but they were there for someone else at least.
Duplicate copies appear as a number in the box with the luxery resource icon. As for duplicate copies from trade, they don't appear because trade deals last 30 turns, so you lose them before your next deal ends. Can't trade away what you're getting in a trade.
The game has a lot of unnessesary clicks, some interfaces should really just be spliced together.
Where?
Why does checking my opponents progress require flipping through 5 seperate victory screens?
It doesn't though? You have a "victory progress" screen which tells you who is ahead, and if you wanna know details, you can click on the victory type and see everything about it. I do not see how they could possibly fit it in one screen, so this is the optimal solution.
Why do I have 4 seperate city interfaces? Rather than just one like in civ 4 and 5? Why do I have to go to a whole different menu to view City Details?
Because you're not looking at all things at the same time, so this greatly reduces clutter. In IV and V you had everything in one screen. I don't know about you, but I'm always struggling with selecting my next build in IV because it's so crammed. In VI you just click on the city once, and then click on 1. Buy land 2. Change production 3. Change worked tiles, 4. Buy stuff or 5. City details. Compare with V: While in V you can immediately buy tiles or change citizens, you still need to press that button for selecting production or buying stuff (typically the most important things), you have a smaller list for production things to work with because everything needs to fit, which means more scrolling, and on top of that Civ VI allows you to swap between cities very easily, which was very much not so in either 4 or 5 (you could go through a list but you couldn't click on any nearby city) and on top of that if you are in a menu, you can
still do that, and you are automatically in that city's menu. It works a lot smoother than either IV or V.
I do guess that merging "buy tile" and "work tile" could be one menu though.
EDIT: And one more thing, in V a lot of space was also taken up by that menu at the right, which showed buildings, wonders, specialists, etc. They're nicely put in each of their own places in VI: Specialists are in the "worked citizens" menu, where they belong, while buildings are easily visible from which buildings you already have, as districts mean you automatically have them sorted nicely, and wonders are visible on the map anyways because they take up tiles.
My biggest personal gripe: Why can't I turn of the animation of menu's? It makes navigation so slooow to have it slide in every time.
What animation? I honestly haven't noticed any animations, so they can't be that long.
Trade proposal doesnt show luxes you are receiving from other civs through trade already (AI often offer a lux another civ is already trading you)
The rumour system is info you get quickly and cant view again. It should not be an alternate to notifications. Thats poor design.
Re: CS notification. Why not bunch them in one notification with a bullet point list in the pull out info. That way all the info is one place and you dont have to work through rught clicking 6 notifications and opening them one at a time. Again an example of poor design making my use of the game more tedious.
AI typically don't offer me any luxeries at all, so that's already one difference. Typically they want my luxeries but I don't take theirs because I consider them too expensive. But the same thing holds true - you may have it now, but in a while you don't anymore.
As for rumours, you actually can view them again. In the leader screen you can see all rumours from that civilization.
A bullet point list is, I would argue, not really something that you could fit in the lower right corner. It would look super ugly, at least. Then again, if you prefer something ugly over right clicking a few times, maybe...