Here's one thing I'll say for this approach in Civ VI: having become accustomed to playing tall in Civ V, it wasn't until Civ VI went too far in the other direction that I realised *just how boring* going tall is. There isn't a lot to do except shuffle units around as you have so little production space. I wouldn't be surprised if this is much of the reason so many people still strongly dislike Civ V, since it seems from the Tradition obsession that not many people were actually exploring how the game plays with more than four cities.
Having essentially no constraints on expansion was not a good move for Civ VI - there's a reason all prior Civ games had mechanisms to constrain it. In Civ VI it seems production is the only limiting factor. Loyalty does a good job of pacing expansion, but only if you're in a Dark Age or the nearest rivals are in a higher Golden Age while you're in a normal one. I like that idea of pacing expansion by Age, but I get the impression that many people play to get a permanent Golden Age which rather undermines the point of the loyalty system.
Civ 6 definitely isn't true ICS in any meaningful sense of the word. For both culture and science victory there is a number of cities after which it is simply not worth settling any more peacefully. That number is around 20-25, from my experience in game.
There is also the point that in a true ICS game you try to settle your cities as close as humanly possible in order to have as many cities as possible. While in Civ 6 the main point of city placement is to get the best district adjacency possible, and at least some source of housing. In Civ 6 you do not necessarilly settle your cities as close as possible (though it is often the case), rather you settle for mountain-range campuses, district triangles, etc. While with true ICS it is mostly the city itself and the city center buildings that made the strategies viable, not their tiles or their positioning or anything like that.
I think it's a very good move that Civ 6 has little penalties on settling. There is still a heavy penalty, which is settler cost. It increases dramatically after 15 settlers in my opinion, so much that it's often not worth it to hardbuild them. You want to get them with gold/faith and monumentality/theocracy bonus ideally. That alone I feel is enough of a penalty.
Realistically, most player probably settle somewhere between 4 and 10 cities in most of their games. For fast win times you want something like 15-25. I don't think that's too much necessarily. Now I don't want to micromanage 150 cities every turn, of course there is some point at which it comes pretty ridiculous, but imho Civ 6 has found kind of a sweet spot.
And we haven't "figured out" the game anyway. Just like in the late stages of Civ 5, people were figuring out that Piety and Liberty could actually also yield good finish times, maybe for Civ 6 we will also see strategies with 10-12 cities that rival those finish times of super wide empires. It's certainly a possibility, it just takes players to be creative.
2. Production balance. Everything simply takes TOO LONG to build.
9. Chopping. I like to build up my infrastructure and land, not destroy it. Yes, you could chop in Civ 5, but the meta in 6 is definitely balanced to chopping and harvesting everything asap, and I hate doing that. I'll do it if I'm rushing a wonder or putting a district there but apart from that I usually never chop or harvest resources.
10. and this is the biggest one... the civ 6 balance/meta seems to be heavily leaning towards spamming out cities (no matter how crappy they are) and killing and conquering as much as possible. I want to build! I'd rather play tall than wide, but that's very hard to justify in 6.
you might want to try playing Maori on a small map and quick speed, and you'd have at least 3 of those fixed
I definitely agree with your point regarding snowballing, most of the time I know I have the game won by t60 r 70 because there is just no way the AI can ever catch up. the problem here is not the player being too strong though, but the AI playing completely suboptimal. If the AI had higher priorities towards campus and lower towards encampments, and higher priority towards mines compared to farms, they'd already be much more competitive. Civ VI doesn't need a lot of changes to have massive impacts on its balance.
It's honestly kind of impressive just how bad the AI is in Civ VI at winning games. Or in general with decisions. It seems they always build the weakest districts/units/tile improvements/Wonders and doesn't research the right techs/civics. Almost like they're making the worst choices possible in most regards.
This would easily be fixed if they just released the source code, and changing the AI preference could genuinely fix this game, I think.
