And obviously you're asking every mapper their authorization, right ?
That screenshot in the first post is the best example. Back Alley was a map made to look, play, feel, sound like a typical 3D-R map. As it is: the map is close to perfection on every point (some argue that it is too short but I disagree, this is how 3D-R style maps are supposed to be, it feels like a map from ep1 or 3).
Now adding all your things from your mod into this map is not what the mapper intended at all, and is most likely going to ruin that "perfection" I was talking about, gameplay-wise.
As long as the mapper in their .txt claim that "bla bla bla you shouldn't use this map as a base bla bla bla" then you shouldn't use those maps in your mod.