I think reactos is just in a weird space of semi uselessness like haiku. It's not good enough to use daily and doesn't have as much retro appeal as game emulators so not enough work is done to it.
Also building reactos is terrible, or at least was years ago (it's a whole os and userland after all, I know it won't be simple). If the development workflow improves the project could get off the ground.
As far as posix support goes I would love to see reactos get to the point where a posix nt personality could be real again, but really I think humanity has learned enough about operating systems to build a new one from scratch instead of liberating proprietary tech at great cost.