Just looking at the game a bit more, I do think the designers really just messed up with the visual style. Urban sprawl and the murky, hard to read maps, are partly due to the way cities unpack too much and spread out (which could be fixed a little with differently scaled maps I guess), but mainly I just think a lot of this is visual design 101 problems.
The designers have just gotten carried away with the little diorama view, the pretty little models, and not considered how these things look at scale. The key here is contrast. The human eye is attuned to contrast and there just isn't enough of it on the maps. Cities blend into rocky environments, colour, scale and shape all just merge into a murky brown sludge. It's not even about going back to the cartoony style of 6, I just feel like basic design decisions early on have set them up for failure. At the highest level I should still be able to make out what kind of tile I'm looking at, where my buildings are roughly what they are. I think designers really only considered what things look like at the closest zoom level.
So I think the the problems are pretty deep in the way the game is designed. I'm not even sure how fixable it is.