This is an interesting discussion. Earlier versions of civ had simpler systems, like defenseless cities, trade units that grant a one-time payment, and many others. The simplicity of the earlier systems let us focus more on how we want to play the game, rather than perhaps thinking about the optimal way to do it. Now that we have a lot of systems, and more complicated ones, they can sometimes clash with our enjoyment of the game and with immersion as well.
I think an example of this are districts. Districts are great, but they're kind of a double-edged sword when it comes to immersion, because they introduce a bunch of pure gameplay decisions and puzzles like
@Arent11 mentioned. You can't have a good science city without jungles or mountains. You have to preplan your city layout in case you want to optimize a building or wonder's radius effect. It feels good to plan out great district spots, but sometimes it gets in the way of actually enjoying the game, like if that ideal spot has a resource that you want to harvest first. From my own perspective, I think I preferred it when ideal play didn't make such a big difference.
Regarding science and culture, I think the idea you mentioned of having a single "ideas" currency could be better.
I think part of the problem is that we're getting a lot of minor decisions and fewer major ones. There's a lot more potential for min-maxing and optimal play, and that conflicts directly with immersion and even enjoyable gameplay sometimes. For people who like to play civ more as a roleplaying game, it can make it harder to get into a flow. Like
@mitsho mentioned, I also prefer experiencing civ as a story rather than as a gameplay experience.
I like the new systems they're adding, especially governors, but I agree, it's probably time to take a look at all decisions we have to make in addition to the systems and yields we have to manage and see what can be changed. A clean start like
@mitsho said.
As a side-note, I've started to notice that some of the ideas are similar to those of Rise of Nations, which I'd recommend any civ player to try! It was designed by Brian Reynolds, the Civ II designer.