1. Builders who instantly build improvements and disappear after few uses give me fell like many mobile strategy games on phones not a real empire building game like old CIVs games
Could you explain what is the relation between how the system works and mobile games, or how it make it be less of a real empire building game? I don't get it. The system is more complex, it require more thought, better timing, it's the complete opposite of what people usually mean by mobile game when they use it to lessen a game and make it look bad. Mobile simplify things to fit that 5 minutes play crowd they are trying to reach, builders with charges are not a simplification. It couldn't be more further from Mobile. As for not feeling like a real empire game, why? Because it take one turn? What make it less of an Empire building game?
Builders with charges are one of the main improvements Civ VI have over V and I'm pretty sure they are here to stay. I'll be surprised if they go back to the old Workers in Civ VII, I expect to see a new take on this same concept of limited builders.
2. Visual style is too cartoonish and also give mobile game fell – this is mostly resolved with mods
That's purely a matter of personal taste. Mobile don't have a monopoly on cartoonish visuals, for me a cartoonish look doesn't make it feel like mobile, just cartoonish. When I saw Civ VI for the same time it was hard to get used to it because it was unexpected. Almost 3 years later I love how it looks.
3. And biggest issue for me is that we cant remove districts this is one of game main problem because we are don't robots which can predicts needs of cities of our empire for entire game. Example on begin of game we need districts which help us to expand and build army and resources after we grow up first cities which we build don't need military and expansion districts so sum of thing which I want to tell is that priorities on game city development is not same in every part of game so we need ability of razing districts which we don’t need anymore that we can replace it with other.
I enjoy planning what I'll do, so for me having to think way ahead is a plus. I love the planning phase, see what will go where, set priorities. I also don't get exactly how you would like to use such a mechanic, aside from correcting district positioning, mostly in a conquered city. You want to actually remove an Encampment just because you "don't need" it, so you can build another district? That would be highly counter productive and make zero sense. I'll be honestly with you, it seems that you didn't play much of Civ VI and is talking from a perspective of someone who didn't play enough to get how the systems works, districts in this case.
Lets take the Encampment as an example. Encampment buildings give production. They also give great general points, which have both combat advantages and a retirement ability. They add specialists slots, which can be worked for more yields. Later they help if you're going for a Scientific victory, giving 15% production towards space projects. You also have Eurekas/Inspirations that rely on them, they are useful for defense, they can be used to increase the adjacency of other districts, there's wonders that require them and probably more minor stuff that doesn't come to my mind now. Point is, there's no such thing as not needing an Encampment anymore, they still useful even if you're not building more units. Same for any other districts, they always give you something, it's always an advantage to have them.
The only thing that could justify removing a district aside form conquered cities is the population limit but it would go against what the game is trying to achieve. Civ VI encourage you to specialize cities. You don't deal with the districts population limit by removing them, you deal with it using planning and growth. Forcing you to choose wisely where and when you gona build a district is the whole point. You can't just spam every district everywhere, so you build an Encampment on your high production city, Campus on your mountain city first while other cities give you your first commercial hubs and so on. You have to choose, think, decide. That's not a draw back, it's the exact experience this kind of game try to offer.
Even for conquered cities I can argue that not being able to remove districts is a plus. It give cities identity of their own. The city is what it is, either take it or leave it. I don't think everything should go perfect for the player, sometimes you have to adapt, sometimes that mean a holy site with zero adjacency in a city that can reach mountains. Life is unfair, the AI have its limits.
Anyway, there's a mod that let you remove districts, so you can play the way you want.
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