I am aware of the current trend on level design in CSGO, the clean looks with almost no detail on the textures but normals or the blurry/washed out textures in the new de_train. Regardless of that you have to take into account this map has been in development for very long and because of that the art direction doesn't follow such style as it wasn't trendy by then. Both maps resemble old games color palette, being rust more obvious to hl series, for example.
As I come from CSS I knew what the scene demanded back then, 1.6 style maps with minimum amount of props and few basic textures all over the map. That's why you may look back to my old map de_rust and feel like it is empty or de_rails and feel like there it is too detail texture wise (the amount of props and details are posterior work I did in order to make it appealing to current standards). As the direction was towards a more detailed style in textures you'll notice visibility is taken into account by using a strong contrast and not by reducing the amount of detail on them. Snow and white walls are a clear example of what I'm talking.
Imo the best way to improve visibility in this point would be to make custom player models with a different color (yellow, orange, red etc) thus not getting rid of the art direction over the map nor the "realistic" texture style. I'd say even more, I'd like that to be viable art direction in our maps as not all themes are suited for the clean style you mention (season, agency etc), and I like the old dirty looks.
Meanwhile, the player models I've chosen have not just white parts but dark ones and I had no difficulty spotting them, but I don't discard those playing for the first time may not know how the map plays, where player might be at and because of that will take them 0,2s more than it would take them if the textures were plain, so they will blame enemy's frag on the map (or the mouse, latency, teammates etc). That's how cs has always been.
Regarding colors, you may find comments on previous versions of the map stating there was not enough color variation, and it was true. Regardless of the details/brushwork I added to upgrade it to the standard level of details, I've just increased the amount of greens as planed and added few touches of orange for places I thought it would fit and would require attention. When I said I may think about adding more color was precisely for that reason, increasing orange in signs/bombspots or just placing pipes to make it easier for 1st time players to notice those CTs sniping in spawn (like I did with the light there).
Imo the colors chosen are fine and not frequent, despite players tend to prefer warm palettes, specially those who have not as much sun as we do here in Barcelona. In any case it's mostly green-brown-white + purple sky&lighting that sets the mood. More than the theme it was the mood what I was aiming for, and I like it. The theme is not different than train, I could place some Russian signs to call it a russian trainstation but it would really add much value to itself. To me it feels lonely, cold and far away from the city (some players even told me without asking it felt like there was a dormitory town in the skybox). Also the whole map theme is consistent, you can't really say you are in a different place at all (that's something I didn't like in the new train with the scifi part for example).
I agree I could've added some iconic stuff to blow up like toxic wastes or a statue, but by the time I started I had no 3d package (so I wasn't planing custom models) nor didn't matter much, I can arrange a story behind like this: "Abandoned in the old train station lies important evidence that may incriminate the main opposing political party in criminal activities. The government has sent the special forces in order to secure this information and disclose the information to the public before the elections take place.". In the end great maps like dust2 or yours de_cache are quite similar, and nobody really cares in the second match.
I appreciate the feedback FMPONE, it is something I'm aware of and I'm taking into account for the map I'm working on right now, but I'm not sure if blurring all the textures of de_rails would be a good idea.
P.S There are some bumps around (v.g white wall, snow...), but as the textures are not plain color/washed out it is not that evident. You may try the commands to see the difference, you'll see it is not huge as there is some shadow information in the color map, but they really help.
Thanks!