Alright then, thank you idragosani for giving me a proper answer. There were talks of porting the MyPaint brush engine to GIMP, which would provide a suitable application for both types of users (Windows support included). But that would require (from what i've understood) converting the library from C++ to C which is a hassle one might not want to bother with. In any case, it's clear that MyPaint is not worth investing much time in. It's great at what it does right now, but there are no prospects of having anything more than that in the foreseeable future.