We don't know what will happen when a nuclear war wiped out 9 out of 10 people in this world, so we can never talk about what makes sense in a post-apocalyptic setting.

This

True, though we do know that radiation does not stop plants from going, we know that the Chinese would most likely have used an air-burst tactic that would both maximize damage and minimize nuclear fallout and that the amount of heat and destruction needed to turn the Capital Wasteland grey for 200 years would have almost completely vaporized the city and yet many buildings are still standing.

Agreed. But I still think something would have happened in 200 years, if only minor things. Then again they do have trade routes and settlements here and there and I don′t think we can expect major changes considering almost everything on the face of the planet was vaporized.

Still...

You are correct, the radiation is quite silly in Fallout 3. However, I don't see why so many use that one flaw to judge the entire setting.

As for buildings still standing Todd Howard said pre-release that they know what happens when you nuke a city but Fallout 3 would be one hell of a boring game if it was all just sand and rubble.
And as for plants - it's just a deign choice. I don't see how the lack of grass and leaves serves as an immersion-killer for so many. Also, physics work differently in Fallout than it does in real world. Viruses are a good example in Fallout where they work nothing like they do in real life.
Well, with all electronics fried, only a few thousand survivors in D.C., all military personnel deployed in China and West Coast, I am not surprised that there is no progress. From what I understand D.C. was a relatively silent place for a great many decades after the War. Super Mutants seem to be a new face in CW, Rivet City was founded only a few decades before, and there can't be more than a few thousand people in the city altogether.
And of course the West Coast saw its first progress not until the 23rd century and we must remember Fallout 2, which still has rather destitute and makeshift cities - is set only 30 years before Fallout 3. Vegas was spared because of House but no other city got that lucky.

Can you explain about the House?

There were 77 nukes coming on Las Vegas. House's defenses disarmed and shot down majority of them and only 8 (IIRC) got through but none hit Vegas itself. Thus the city was spared.

Ah, thanks!

It would. As it is, it makes little to no sense.

When I first played it, I thought, did the war happen 2yrs ago or 200yrs? Looks more like 2.

It isn't the lack of plant life that kills the immersion for me, it's the inconsistencies that do it. I just feel that if Todd Howard wanted most of the buildings intact then he could have come with an excuse like DC, being the capital, had extremely good anti air protection and thus it was saved from the majority of missiles though sabotage by Chinese spies disguised as workers at a local food processing plant(Mama Dolce's) caused some of the missiles to break through its defenses which caused the deaths of the majority of the population and the destruction of some of its buildings.

Instead the only explanation we get from Bethesda is that it would be boring if it was all just sand and rubble so they took more then a few liberties with science and the lore. The truth is that I wouldn't be so annoyed with all of the inconsistencies if they had just given an explanation as to why, but it seems that Bethesda wasn't even willing to do that.

The West Coast didn't just progress in the 23rd century. They had quite a large towns, trade routes and other crap only a couple decades after the Great War. The Great Merchant Wars in the Hub, they were fighting over a developted city.

I did not follow the pre-release stuff frankly, and what I said earlier I heard later on this forum. True, the most likely scenario is that Bethesda never directly explained how D.C. is not entirely destroyed, but I don't see a real problem with that. It seems nitpicky and focusing on the wrong detail.
You are true about the Merchant War, but California is the most populated state in the US, one of the largest ones and Fallout 1 was set in almost all of it. Only one city, the Hub, had some remarkable progress in it with Junktown, Boneyard and Necropolis lagging far behind. In Fallout 2 we have the NCR which is certainly worthy, then the Vault City which has only 100 people in there, Redding which is hardly an advanced town and New Reno which is even worse than it could be without its current system. Of course there is also San Fransisco as well, though it's more of a Chinese city.

Fallout 3 is set in a single city, the number one target in any nuclear war, I don't see sense in drawing comparisons between the two coasts to discredit Fallout 3. Not saying that you are trying it, of course.

I'm just focusing on this one issue because I want to stay on topic and I don't want to devolve this thread into a 'which is the best Fallout' shoutfest. As for the inconsistencies, when I first played Fallout 3(my first Fallout) I didn't notice them, I just loved the game because it was so new to me. It took the combined efforts of New Vegas, Fallout 1 and 2, plus another playthrough of Fallout 3 to allow me to see all of the mistakes. It is one of the main reasons why I'm not sure when my next playthrough of Fallout 3 will be, plus I don't really consider my problems with the Capital Wasteland 'nitpicky' though that is my opinion. I'm not saying that an explanation by Bethesda about the different levels of destruction in the DC wasteland would have completely appeased me, but at least some acknowledgment by an NPC would mean that they were at least trying.

Anyways, this is what I think of the colour of the Capital Wasteland.

Even in the other towns they have more progress, you can help the Boneyard with thier hydroponic farms, I don't think anybody in DC even knows what that means. Redding was pretty advanced, mining equipment and corporations and New Reno even being devastated by gang warfare had things like movie theaters, mass stills, drug labs, etc.

I just think after so many years that the radiation in DC would have subsided and they could have used all that stone from the collapsed buildings to make houses not made by nailing pieces of metal together.

True, the dull colours get tiresome fairly quick, but they add to the atmosphere. Although I'm also one that hopes over to Oblivion once in a while for a break.