Perhaps a recent Reddit post of mine fits here:
IV is the last true Civilization game. That is, an empire-builder game. Indeed, Civilization V's optimum strategy is building three cities, ever.
From I to IV, including Alpha Centauri and Revolution, Civilization was about empire-building, about expanding over a whole wide world, immersing oneself, conducting diplomacy, building up your civilisation. V and VI ditched this fundamental vision of what a Civilization game is.
For one, they lack meaningful diplomacy and other AI interaction. They lack an AI that makes sense. Seeing '-1 Our close borders spark tension' and such factors is vital to that, so that you can clearly see 'ah, yes, I see why this AI dislikes me'. AIs should have friends, and should be angry at you if you declare war on their friends, or if you trade with their enemies, so that different blocs may form of AIs that like each other. That is miles better than the warmongering penalty of VI that everyone ignores, or the intrusive denouncement pop-up that doesn't matter a lot. Further, it is better than irrational agendas - complaining about not having nuclear weapons in the Ancient Age, or outright contradictions between two agendas - and irrational AI behaviour in general; a 'play to win' AI is inherently not an AI that is conductive to immersion.
One good thing; AIs still have their own personalities (some prefer gold over science, some care more about sharing the same civics over sharing the same religion, some prefer building units while others prefer building wonders...).
And mind, these are personal opinions; you might care more about competitive play, about winning the game, instead of being the co-author of a story, of watching history unfold in your game, and such things. That is perfectly fine! But this change of focus is a step away from how Civilization was in the past, even if they halfheartedly tried to rectify it (adding visible modifiers to V, adding agendas to VI - it's lacklustre and not enough, to me, but still).
For two, the newer Civilization games lack scale. IV works on a larger scale than the latter Civilization games, which reduce this scale in a variety of ways; one unit per tile, ranged attacks, a minimum city distance of three, three rows of tiles to work for cities, one district per tile in VI, smaller maps, and so on. All these mechanics serve to reduce the scale. Arguably, irrelevancies like archaeology reduce this scale even further. And even making roads have an upkeep cost contribute to this more tactical, or medieval-esque feeling, as opposed to an empire-builder. The newer Civilization games play more like a medieval-fantasty tactical wargame, such as Warlock: Master of the Arcane (ironically, I would argue that IV's warfare has more strategic depth than V's, but let's not clutter this post).
Was IV the best, regarding scale? No, III had the largest scale. You can pretty clearly see this if you simply compare random screenshots from Google. Count how many tiles, and cities, you see in a screenshot. III's maps were also the largest, both objectively and subjectively (one unit per tile and all serve to make the maps seem even smaller).
I think these two points are the main points that make the newer Civilization games feel so different. One can, of course, pinpoint underlying mechanics, but they serve to add to the above feelings. One unit per tile is the most important point here, that I have not addressed yet. Entire epics have been written of it by now. An important point - more important than being the last piece of a paragraph, but alas - to note is the interface; IV's interface had its problems, but it is objectively (yes, as in, verifiable) orders of magnitudes better than V and VI, and this truly cannot be overestimated. But it has little to do with immersion and scale, so I won't further comment on it.
There are plenty of other mechanics that I have opinions about. VI's implementation of religion is terrible - but V's one was superior to IV! V, too, found more uses for culture, making it matter on a global level, which was also a very nice change compared to IV. Hexes are also probably better than tiles.
Or the whole concept of 'wide versus tall', which is a dichotomy that should never have been invented. 'Wide' must inherently be better, otherwise you do not have an empire-builder game (what value, then, has land? But wanting more land is inherently part of 4X, and a core part of empire-building). And yes, any tile where you place a city will always be better than any other tile, because this city-tile can contain dozens of buildings that yield so much (and on that note; Civilization V uses a lot more +flat yield modifiers than Civilization IV, where buildings all use +percentage yields). So the optimal strategy is to create a city in every single spot where you can.
But that is only the optimal strategy over an infinity of time. Civilization III's corruption mattered little; receiving one production and one gold, instead of ten, is still a profit. Civilization V's global happiness was downright silly and had more or less the same effect; produce a Colosseum somewhere and done. In both games, REX'ing was obviously the superior tactic, and this was only changed when Civilization V started increasing the science cost for all future technologies - and that resulted in the optimum strategy being only ever building three cities. Civilization IV had the perfect solution here; maintenance costs. Establishing new cities cut into your gold production, a lot, and because gold and science were coupled, expanding too fast could leave you poor, backwards, and an easy target for any aggressive neighbours.
You can see that the Civilization games are quite complex, and that many of these mechanics are interconnected; the way you choose to counter REX'ing can have - and has, as far as V goes - a direct impact on the scale and the feeling of the game.
One unit per tile has that even moreso, but Sulla can explain that far better than I can. So finally, I would ask you to read this article:
http://www.sullla.com/Civ5/whatwentwrong.html (and, while you're at it:
http://www.sullla.com/Civ5/bnwreview.html ).
In the end, it is perfectly fine that you prefer Civilization V and / or VI. You enjoy them, and why should I force what I like upon someone who doesn't like what I like? It's nice that you enjoy these games. That does not take away from the point that the Civilization games, the fundamental core of what they are, changed with V, VI, and Beyond Earth. Shafer - V's developer - all but admitted that, seeking to recreate Panzer Generals - a tactical wargame - in a suit of Civilization - an empire-builder game. You may like that development. That is good for you, truly. This post is not meant to be an attack, or a sneer, or a rant about how the things that I enjoy are obviously superior to the things that you enjoy. Because they aren't.
