First of all: Style creators are encouraged to
only use background colors when it is absolutely necessary. Like the dark blue background in the crystal style to be able to see the black terrain. Therefore level designers that do
not want to use the default colors (which is black in most cases anyway), should think for a bit whether they actually want this. I know you two do that, but still I prefer to make going against the style's wishes non-trivial.
Having said that: I totally agree that the current situation is not perfect. But we are at the moment moving from "You have to decide on one style" to "You are totally free in mixing styles and colors". So long-term I would prefer to remove "main styles" completely and put the colors directly in the level files (of course keeping backwards compatibility), which then can be modified separately in the editor. But we are not there yet. So for the meantime I would really like to discourage stuff that would have a proper solution later on, while adding extra things I have to keep supporting.
...remove it if/when background colour picking is added
theres a few other block colour backgrounds already anyway
You have missed all the huge discussions when I wanted to remove stuff from NeoLemmix. The lesson for me is: Oppose the addition already, because removing is soooooo much harder. Unfortunately, I was too late for the other single-color backgrounds...