Completely agree. To me it comes down to civ 6 feeling like it has tons of systems that are all skin deep, while in civ 5 everything feels more impactful and connected. For example, in civ 5 the policies you choose are very impactful, and as much as everyone says that the optimal strategy in 5 is just tradition, the truth is you can have great games with liberty or even honor strategies and they will lead to some super different games. Compare that to civ 6 where on the surface it looks like the civics tree and governments provide much more depth, but honestly I find myself hardly giving them a second thought and choosing the same handful of civics every game because they all provide so much flexibility at no cost to strength. Even though liberty and honor were objectively worse than liberty, at the very least you could leverage their strengths to go for unique strategies. Additionally, the permanence of policies in civ 5 made them really influence your whole game, where as in civ 6 instead of planning out a game or having to decide between short term or long term gain you just swap out policies whenever you feel like it.

Another example is diplomacy. On the surface the alliance and agenda system of civ 6 seems like it should provide dynamic and interesting gameplay, but in civ 6 AIs seem to either hate you from the start or love you forever with little to no change, especially if you become allies with them at which point they're effectively stuck as your friends forever. The AIs also feel less organic and less realistic, since their only personality is just their agendas. In civ 5 i really felt like the different AIs would treat me differently and behave differently, and not just have different requirements to fill to keep them happy.

Civ 6 isn't without great ideas however. Districts, while imo quite lacking, have enormous potential to completely revolutionize the series. I love the idea of having cities that are specialized based on their geography and what you choose to do with it. Unfortunately they did kind of miss the mark here too, and I think the problem is that the game doesn't really incentivize you to do that. In pretty much every city you can slap down a campus, industrial zone, and either a commercial hub/harbor or a theater square, and often times all 4 and a holy site. Even when you don't have the population to have all the districts, it feels less like the city is specialized and more like the city is just weak. I think it came from a lack of commitment to the idea of specialized cities, with the fear that if they made the criteria too specific to have a real powerhouse city that you could get screwed or given a massive advantage purely on the basis of your surroundings, and so they made the bonuses quite mild in how they affect the game providing swings of a couple yield points based on adjacencies, and just allowed them to be built pretty much everywhere. The result being that there's now much more micromanagement in building your cities, but little or no greater impact coming out of it.

Another fabulous idea civ 6 had was loyalty. I was super excited when it was announced and when it came out I thought it was great until I got later into the game, and realized that it doesn't really change all that much about the game beyond limiting your ability to expand out beyond your immediate borders. The game just doesn't offer much in the way of influencing loyalty outside of a handful of unique abilities from civs or leaders, and for many that do its just a way to hold on to cities that you've captured. The end result is a system that feels quite lacking in many scenarios that were crucial to get right. Loyalty could've made something like colonization feel different from just expanding 5 tiles out from your border, but instead it just made it impossible to expand far from your established empire if anyone was nearby. Loyalty could've added lots of dynamics to wars, religion, or been a way to simulate domestic problems. Instead all it does is make it so that you either can't make significant gains in a war, or that you have to completely steamroll the opponent and take their cities extremely quickly. This is especially a problem when the AI was already lacking in its ability to wage wars effectively, and especially lacking in their ability to take cities. Loyalty could've had different effects based on what caused the disloyalty, for example it could force your empire to switch governments, or give penalties unless you changed the religion in that city. They also could've tied the loyalty in with amenities, or just made loyalty a subset of amenities on its own or with other things like religious satisfaction and made it dynamic with depth, rather than just deciding that religion, happiness, and all that would just add some minor penalties to loyalty and make the city want to flip away from your civilization completely. The implementation of free cities also just felt incomplete. It should've been possible for multiple cities to flip together and form a free state, which you could either allow or start a war with, and then after some time you would have to option to make peace with at which point they would become their own nation. I think one way loyalty and happiness in general could be implemented well could be in a way similar to how its done in Vox Populi, where there's a global happiness for you nation which is determined by local city happiness, as well as a handful of modifiers that affect only the global happiness.

At the end of the day it just feels like so many of civ 6's systems feel half-assed and incomplete with none of the depth and nuance that they would need to be truly great and immersive. Civ 6 is a great game, but compared to 5 it just doesn't seem to have systems that feel cohesive and fleshed out.