I could not agree more. I tried to add support for Linux to my own framework (Jamba) and had to stop because of this exact issue. I posted a few threads/questions that never got any answer:
It is very obvious that Linux is a second class citizen (no Plugin Test Host, no support for timer/ui thread, many pieces of code with “warning TODO: Implementation” when compiling for Linux leading to things like Drag’n’Drop not working, and much more…)