I prefer consistency over what civ 2 gave us. 3 must be awful... I can't even remember
I prefer art styles that give me immersion over very strict forms of consistency
And mixed types of art, real footage, 3d models, 2D art and so on, can work very well together and create its own consistency. Some people who aren’t used to it might think that it is strange at first, but they will often get used to it, or even love it if they aren’t very close-minded.
This sort of thing was much more common in computer games in the 90’s. Especially after the introduction of CD-ROM media. Civ 2 is a well known example here. Another one is the fantastic open-world RPG Might and Magic 6 from 1998.
It mixes together real 3D, pre-rendered 3D, some 2D artwork and for the NPC’s you talk to, their portraits are mostly made up of real people dressed up in “period” clothing. Seeing real people in a game like that feels a little unusual at first for many people. But it seems like it was a good choice, and many people seems to appreciate the unique style it uses. Unfortunately for Might and Magic 7 they used only 3D and pre-rendered 3D, and that game has a blander look.
Not sure how, as good as they were, you can claim 4's were better than 6's. It's almost the same thing, but without the very cool situating in your own world.
You are spot-on that they are almost the same thing with a small difference. But that small difference apparently makes an important difference for both you and me, only in different ways.
For me, getting momentarily taken away from the game in Civ 4 and shown something that is almost like a short ”documentary” or presentation, makes it more immersive. In Civ 6, seeing them getting built on the map was a neat effect, but it wasn’t that immersive for me, since I never connected much with the map in Civ 6. I find it hard to imagine the buildings in Civ 6 as either a representation of cities in a geographical region, or actual buildings in a city. Different strokes I guess.