Yes we need something is not in zbrush currently. But i have some word about this part of your writing.
Look at this quote from Mudbux 2012 new features:
UV-Less Painting: Enjoy the freedom of not having to create UVs before you paint! Texture artists can now eliminate or reduce the time-consuming and often difficult task of creating UVs; even complex assets comprised of multiple meshes can simply be loaded, and painted right away. The resulting high-quality textures can be exported as…
Don’t you thing they try to make a similar thing like that you say ZolyPaint?
And Zbrush have this for many years.
Yes Zbrush have bugs, any software have bugs. We use 3ds max az primery 3d software in our company and we say **** words to autodesk for all that overlooked bugs in it but still we love it !!!