I do prefer the floor to be a single color...
A single color floor (if the corresponding Backdrop floor is not also a single color) moves the combat visuals away from realism and in the direction of the abstract, iconic, and symbolic. This represents a deliberate step away from the natural world which allows, if not evokes, a different reaction in the viewer, as a participant in the art, from what would be their most natural reaction to the subject. Other thoughts and emotions, different focuses and perspectives, are invited into the process.
That, of course, may be an unintended consequence to some artists whose interest is merely to better showcase the art of the combat icons, or to simplify and sharpen the elements in conflict. Still, it is of real consequence to the gaming experience.
It is something I've given a lot of thought to, over the years. I've probably created more Combat Dungeons than any other FRUArtist, even more than the wonderful Suzanne M. Ferree (I fondly remember our many discussions and exchanges of ideas about Combat Dungeons). After all the time and experimentation I've done with them, I still use both realistic and abstract approaches according to what I believe are the needs of the Combat Dungeons themselves, and also the context of the mod they will appear in.
For example, below I have one of my earliest Combat Dungeons, from "Fire and Water
." The technique is a bit crude by my current standards, but you can compare the effect of the single color floor against that of my second example, which is from my most recent OAUA design, "The Snow-Woman's Daughters
." (In both games, the flames color-cycle.)
The first game was very light-hearted, while the second was one of my most serious attempts at a darker, intensely dramatic storyline. I believe that if I had put in a single color floor in the second, it would have detracted from my goal of realism for that mod, at least to some degree.
My point, simply, is to suggest to our authors that there are other considerations to weigh besides combat dynamics and icon aesthetics, alone. My own belief is that sometimes single color floors are best, and sometimes not.