I'm curious to know what the Windows compiler usage/breakdown is. My sense from this list is that many use mingw et al. I don't and I imagine that most people that are developing *for* Windows use VS.
Of course, if your *supporting* Windows, it makes sense to use some kind of unix-ish mini library, and this probably describes the majority of module authors. It doesn't seem to hit the mark for most people that are likely using it as their primary platform.
I think this is also true with people that are poking around, probably using Notepad++.
Imagine you're using some binary distro of Lua. You want to use something that is only in source. You don't normally use C compilers and you're not a *nix guy. So, you'll be downloading the free version of VS. Then you find that your binaries require one of two different unix wrappers (not completely compatible, either). "Crap. Now I need to install Linux?" (I know... But that's the impression people are left with)
Also, with LR and LD, I believe that the directory layout within Windows continues to be an issue, although this may have changed. The Program Files directory (mirrored for x64 and not) can house the core install and %USERPROFILES% can hold the modules in a sub-tree structure that apes *nix. That is, unless some kind of "all users" flag is set, and then it could go that profile dir. I think the journey that TeX Live! and MikTeX took would be instructive. Both did it "their own way, thankyouverymuch" and now I believe that they do that "less so," opting to behave like first class citizens, as much as could be expected. The layout for Windows applications is not very different from /usr/local/..., although I much prefer that style.
Then again, in my dev ENV, everything is in an OSX like .app directory, where everything is organized in the unix way. It's a little different when you're using Lua as an embedded library, though.
BTW: I can always figure out what I need to do from a make file. ALWAYS. I'm about 90% effective with a .config file. 35%ish from CMake and 0 for 3 with slingshot.