Ok, since being facitious is lost via text I'll outline it completely.
The further along the timeline gets the more progressed the country should be. The idea is how humanity survives/ interacts (in groups as well) after a nuclear FALLOUT. 200 years after the FALLOUT the country should be pretty well recouped. I don't want to play that game. The fun part of FO3 was seeing a destroyed territory for the most part frozen in 1950's sci-fi culture. There is a very good reason why the game is popular, exploring destroyed areas that seem untouched for the most part and struggling to survive is adventurous. Seeing bloated powers battle for territory is not interesting to me. I don't want to play that game. Regardless of the original intent of the Fallout series the "survival" part of the game is what makes it unique. You aren't surviving in a jungle, or in a warzone, or a zombie apacalypse; it's surviving a nuclear FALLOUT. This is why I would like to see a "spinoff" (check the title of the forum) not set in chronological order. Let's see what happened in those gaps. Keep the fallout in Fallout. Once everything is rebuilt it's vanilla, watered down, bland. Why would anyone make a video game based on a conflict point that is already resolved?
Fallout New Vegas was great and it showed progression.
Look at Honest Hearts, it was about tribal warfare.
Point Lookout and The Pitt are also strong contenders for why it still works.
Just cause the wasteland progresses doesn't mean that it becomes boring.
There are still interesting storylines that can be told despite civilization returning.
For example, let's take my suggestion for a town called Steam-Ville.
After the war it remained pretty much untouched, some scavengers occasionally salvaged parts of this steam-punk environment but it wasn't until the Trogs emerged out of their caves that it started working again.
Once they got it working and word got around, Sandmen came in large numbers for it's high temprature which they love as much as ghouls love radiation.
The Trogs felt that it became too crowded and started turning down Sandmen, the ones who were already in this town revolted and violently took it over, forcing the Trogs out.
As of 2295 the area around Steam-Ville is hardly civilized. Steam-Ville has a subtle racism and bigotry concerning other races and considers Sandmen to be a "better race".
So it has bigotry going down against humans and Trogs that try to find shelter there.
Since it's banishment of the original Trogs a new Trog faction (Let's call it... Bleeding Sand) arose which dedicates itself to killing Sandmen because of strong grudges.
The Sandmen are spreading their borders, expanding, consuming everything around them and enforcing their culture onto others.
The other communities are getting scared of the Sandmen expansion and the Bleeding Sand is now using this to their advantage, trying to convince the communities to act aggressively against the Sandmen and Steamville, but not because they are afraid of their culture, but because they want to perform genocide on the Sandmen community.
In this area there is are half a dozen drug runner factions who constantly wage war against each other in order to gain firm control over the drugtrade.
We have raiders that are causing problems.
We have tribals that are becoming aggressive against civilized communities for taking their sacred lands.
We have war.
Despite it being 218 years there is still war going on. No faction has been able to take control of the area and bring law and order.
The only one who are doing it are the Sandmen, but they bring a society in which any other race are lesser beings.
So "going forward is harmful to the setting" is bullcrap.
[edit]
This is of course a very crude pitch, but if I can come up with something then I'm sure professional writers can too.
But just cause things become more civilized doesn't mean Fallout will end, sure, the "war... War never ends..." Will be thrown out the window as there will be less and less combat, but combat isn't necessary for an RPG.
Just look at Sims. Fantastic RPG series that doesn't have a shred of combat.
It has death, but not combat where things "die".