Competely disagree. Civilization V has been dumbed-down but not to the extent like other games in the past. This is still a big, sprawling game just Civilization 1 was. It is more refined of course but there are two things I abosultely think should have been kept in.
In my experience, when someone uses the words "Dumbed Down" they tend to believe the changes that have happened are bad. People who like the changes will use words like "Simplified" or "Streamlined" or "Elegantly Adjusted". Right off the bat we understand that you're not a fan.
Corruption and Pollution. Corruption was everyone's enemy but it is a natural part of how human states are run. It provided a challenge for players and forced them to take certain actions to combat it. You say that this is tiresome or it gets away from the 'big' picture.
The difficulty with both corruption and pollution is that they were difficult to control. They made sense
conceptually, but from a gameplay perspective were largely random and frustrating.
Big picture be damned. I want every city to be indivdual and micromanaged to the microscopic level(Well, a level that is reasonable for a gam not a simulation like simcity 4 with water pipes, crime and aging populations).
One must be careful that micro-management be viable, but not necessary in a game. A lack of player control will frustrate people who wish to delve deeper into the game, but forcing too much player control will frustrate people who just want the game to go.
Pollution. A part of daily life that cannot be ignored. Pollution in civilization 3 showcased the issues that arose with the industrial revolution. One cannot just build tons of coal power plants forever and expect not for there to be consquences. The player must micromanage and determine which cities benefit from a heavy industrial transition and also determine which ones do not.
But what consequences? This is, after all, a game, and a strategy game at that. Any consequences that get dealt out need to be perceived and understood. Randomly making certain tiles useless is a bad way to go about that, as it is well without the player's control.
One of the nice touches to heavy industrialization was global warming. Now, I don't necessarily agree with all the theories says but the planet is warming and humanity is having some impact. The appearance of tiles turning to desert demonstrated the consquences of the industrial era that the game world just went through.
But from a gameplay standpoint, potentially disastrous. In truth, you aren't making any kind of choice between "Causing Global Warming" or "Not Causing Global Warming." Global warming, in the game, is a side-effect of advancement. If you choose not to advance your civilization, then you will fall behind those that move forward, and global warming will most likely happen anyway. This makes it a moot choice, and a frustrating game mechanic at that.
These two things added much to Civilization 3, a game I never master but enjoyed at warlord(I am pretty bad but I try very hard and I love the complexity). They punished the player and I think that is important in any sort of game. Reward the player yes but make sure you make the failures hurt hard. Just like in chess.
But in chess, all failures and losses are perceivable and not at all random. Imagine playing a game of chess where, every now and then, a tile explodes and kills whatever unit was in it. Most times it will take out either a pawn, or nothing, statistically speaking, but there will certainly be the times where it takes out a Rook, or a Queen, or the King. This would make the game of chess a pointless game for children, and not the foundational building block of strategic gaming as we've come to know it.