High content, big budget, games still exist, e.g. Elden Ring + Zelda (as someone mentioned) are two recent releases.
There's also plenty of sim games in the indie market, Factorio, Banished, Frostpunk. Then things that are close to the market like They Are Billions, Kenshi, etc. to name a few I've personally had time to play. Kenshi is a bit rough around the edges, but absolutely brilliant in terms of sandbox play.
There's also the Endless series from Amplitutde studios, Endless Legend, Endless Space 1 + 2, that are of a vein of Civ games, plus they've recently brought out Humandkind (though to mixed reviews unfortunately).
The popular sim genre in recent times has been more 3rd person building mixed with exploration, there was the wave of multiplayer ones like Minecraft, Rust, Arc Evolved, etc. And then single player ones like Subnautica, etc.
So there's stuff out there if you want it, it's just not a very popular genre at the moment.
The difference with sim/4X/any genre that's fallen outside of the general "popular games" trend is that they ended up becoming overly specialized and inaccessible to newcomers.
Yes, technically you can still play a bunch of cool 4X games, but most people still making them (with the exception of like, CAs Total War, which also notably defocused the 4X part in favor of RTS combat) is copying the Paradox approach and Paradox is largely known for its absurd depth and mechanics... which unfortunately translates to the games devolving into spreadsheet simulators with fancy graphics.
Civilization was the right mix between "flavorful civilizations", "fun endgoals" and "reasonable to achieve victory against the computer". Most 4X games, because they copied the Paradox approach, kinda suffer from the fact that they pretty much demand immediate mastery of the systems if you want to succeed, unless you're playing with friends (in which case you have more control over each other's bumbling and one person can just hyperfocus on learning one system, while the other can focus on another.)
Its the difference between SimCity and Cities: Skylines. SimCity (before the final game) is a sandbox toy that lets you build a super dysfunctional city but y'know, as long as the taxes don't go in the red, you're doing fine! Cities: Skylines otoh has way harsher feedback tools if you don't build a highly functional city. That's fine if you're already tuned in on SimCity as a game and crave a higher challenge, but if you're new to these kinds of games, Cities: Skylines is just too much.
I would love if Total War games had more complex strategic layer... The battles itself are great enough, maybe besides dumb AI sometimes and balance. On the other hand I had a lot of fun before campaign map economy became just balancing income and happiness. On the other hand, I never thought having armies a discrete entities on the map Heroes 3 style actually added any depth to the game.
Sim City 3000 was my most favorite sim game, while the sims (one) and zoo tycoon (one) follow close. That is until I tried Factorio, man that game got the title Cracktorio for a reason and elevated sim games to a new level. Since then I don't have any courage to try Rimworld, don't want my addiction to relapse.
The others help your point but Cities Skylines is memed because it's graphics over substance as it's basically a city painting game with shallow mechanics that most people use to make little city dioramas which is still fun but not deep gameplay.
The transportation mechanics in Skylines are quite complex and fun. The player can trace individual trips, and some of them matter quite a lot: the businesses need to get and ship their raw materials and finished goods, and the shops need customers.
The budget mechanics are a joke, before long the player has practically endless money.
I'm afraid I must disagree here. I enjoy C:S. But its mechanics are shallow compared to many other titles.
One rather unknown point that, while not directly related, highlights this is how in C:S your income depends on your current budget. I.e. you magically receive less income if you have 10 million in the bank, and receive more if you're in debt. That point alone makes objectively comparing and strategizing unnecessarily hard, and it feels like the game really does not want you to work with numbers instead of paint buckets.
The core of the game clearly is urban planning - properly designing your city to avoid traffic jam and allow the ressource to flow where they need to go - not budgeting. The game doesn't want you to heavily work with numbers because, well, that's not very fun. The budget is mostly there to set the pace.
It has deeper micromanagement than, say, Planet Coaster, but it is not on the level of gameplay loop micromanagement as the like of SimCity or Roller Coaster Tycoon
My issue with the Paradox games is that they have gotten too complicated for their AI, which suuucks. Hearts of Iron's AI has no understanding of its own military strategies, and I don't know how I could have a multiplayer game lasting 80 hours with multiple friends.
There's also plenty of sim games in the indie market, Factorio, Banished, Frostpunk. Then things that are close to the market like They Are Billions, Kenshi, etc. to name a few I've personally had time to play. Kenshi is a bit rough around the edges, but absolutely brilliant in terms of sandbox play.
There's also the Endless series from Amplitutde studios, Endless Legend, Endless Space 1 + 2, that are of a vein of Civ games, plus they've recently brought out Humandkind (though to mixed reviews unfortunately).
The popular sim genre in recent times has been more 3rd person building mixed with exploration, there was the wave of multiplayer ones like Minecraft, Rust, Arc Evolved, etc. And then single player ones like Subnautica, etc.
So there's stuff out there if you want it, it's just not a very popular genre at the moment.