Well, don't just chuck stuff around randomly. Look at 2Fort's spawn room again:

It combines good brushwork and props to create a scene, but the central area that players walk through is relatively unobstructed. Most of the details are off to the side. And the details aren't random, either- the map does a good job of creating a realistic scene, but the details don't interrupt the gameplay or layout of the map.
You're letting your map style interfere with your gameplay. We cannot emphasize this enough:
The map's gameplay is much more important than its style. Sure, it's okay to have a general sense of what you want your map to look like before you create the layout, but sometimes you will need to make sacrifices in terms of realisticness and design in order to make a better designed map. And sometimes, the design and setting that you want for a map just isn't compatible with TF2's gameplay. Large open spaces with no way around them are a big no-no in TF2; they make snipers overpowered, and thus put every other class at a disadvantage. For example, before the MvM competition I was working on an attack/defend map set in a ski resort. The ski resort in the map was based on a real-life ski resort, but many things had to be changed, and some of the changes that I made simply wouldn't make sense in the real world, but I did it for the purpose of creating fun, well-balanced gameplay.