We can all agree that it doesn't work. The interesting question is WHY it doesn't work.
And real life reasoning doesn't work. This is an abstraction.
Both statements are connected with each other.
First, global happiness is immersion breaking, as it contradicts everything we know from real life experiences.
When there were those riots in San Francisco over the police killing a black american some years ago, this did not influence anything in New York, nor in Cornhole, Alabama.
When a friend of yours is really upset about some thing, it doesn't stop you having sex with your wife (reduced growth).
Second, as we all know, in the current version global happiness doesn't stop horizontal growth, it makes it even better.
Third, after the patch the whole system will be even more obscene. While a city growth at the other end of the world can stop your whole empire from growing, you don't have any chance to counter that in your core region.
Fourth, it is a major design fault. Shafer transferred the problems of one location to your whole empire in his attempts to punish the player for not playing as he, Shafer, thinks you have to play (regardless of map size, game speed, circumstances and whatnotever).
So, we have a system which doesn't comply with real life experiences, which doesn't work currently and which will become even more tedious in the future.
Looks to me like pretty much the description of very bad design.
Do static happiness buildings with the unhappiness being generated from population work? If it does, do we just have the numbers set wrong, or is it the system itself? Can it be solved by a tweak or do we need to change around the functions at which the happiness/unhappiness is generated, or do we need to change the system around entirely?
Static happiness from buildings did work in previous game versions, since happiness was local.
Static happiness to a certain extend even works in the current patch version, since that way both, happiness and unhappiness are on the same global level.
Static happiness from buildings capped at the current population size will not work, as now happiness is local again, whilst unhappiness is still global.
The major flaw in the current patch version is that colosseums are much too powerful for their costs and come much too early for their power.
The idea seems to have been something like margin utility, but it wasn't set up properly.
The whole idea is broken.
Happiness works with the numbers of people you have. This number is very low.
Let us assume an empire with 5 cities of size 12, and 15 cities of size 4 each.
Quite some empire in terms of Civ5.
Yet, the total number of people is still just 120.
Having only one new colosseum effects a 3,33% of you whole empire.
Assuming that your empire is at happiness 0, only one new citizen (0.8%) brings down your empire.
Not only this, but you are taken hostage by the city governors.
Best example is gaining new cities due to peace treaties.
You are going into the red happiness-wise, and the city governors will let people in the puppeted cities starve, without you having any chance to avoid this.
Currently, you would have the chance to rush happiness buildings somewhere else.
In future, your new people will just starve until a new balance is found.
Take into account that the new cities will increase your cultural costs, and it becomes obvioius that the whole system is set up to punish you for becoming bigger.
This may adress ICS, yes. But it severely punishes any bigger empire, regardless of how and why it became big.
As happiness is only a sub-system in the context of the whole game, I don't see options to fix happiness without adressing the whole game set-up.
Happiness interacts with very low production, which is low, since cultural expansion avoids "production hexes" as long as ever possible.
On the other hand, except for very small maps, you are literally forced to have quite some cities (causing unhapiness again) to get access to luxuries.
It all comes down to one thing: the main idea behind Civ5 was to play on small maps, a handful of cities, almost no military, just another handful of so-called opponents and then after three hours of "playing", to win.
That's the core concept of Civ5.
Nothing about creating an empire. Nothing about standing "the test of time".
Civ5 is a small dish for in between, to be consumed hastily.
It is the fastfood version of a civilization game.