As the title says, has this been an option that could be added to TSW 2? The main benefits would be to hide/mask some of those really, ugly looking and plain hills and/or scenery. Secondly, depth of field makes things 'seem' further away to the player than they actually are. We've all come across the situation where there is that one random tree placed on top of a hill and you think to yourself really? When in real life there are several trees, many miles away. It also makes things like hills, mountains and yards seem a lot bigger, rather than it feeling like a model railway world. Another thing it does is hide some of those really low level of detail objects placed in the distance, but can still be seen quite clearly from the player. The idea of these low LOD objects is to be placed in the distance, to fill it up, however in TSW it doesn't quite do the job as it can be seen quite clearly. Here's a screenshot from another train simulation game, showing the effects of depth of field. As you can see you get the feeling of a big yard approaching, as well as the objects in the distance having that natural blur as the fog covers it up.
Depth of field is something we discussed just last week as part of a broader discussion. So, in terms of "thought of" - yes.
If so I hope there is an option to turn it off. Just like the ever so wonderful motion blur, which I'm glad does have an option to disable.