Qt, zlib, etc. are different because they have no interest in VTK. I don’t expect them to help to make life of VTK developers easier.
VTK’s long-term success highly depends on how well suited it as an algorithm/library development platform. If there is no easy way to distribute VTK-based libraries as packages on PyPI then developers will spend their time, effort, and funding on VTK competitors.
It should be already possible to create and maintain VTK-based Python packages but I don’t know about any examples. Please give us a pointer to at least one project that can serve as an example for us to follow.
The best that I could imagine would be if VTK developers would maintain non-essential features in such VTK-based external packages, because we would then have lots of examples, they would be guaranteed to be up-to-date, and interests of VTK core developers would be naturally aligned with interests of VTK-based library developers. It would also make VTK truly modular and much smaller.