VTK shouldn't require proj
At least for Fedora 34, VTK requires proj, which, when installed, contains a folder /usr/share/proj that has a size of over 500 MB. I am currently working on a Docker image which in its entirety has a size of 2.5 GB, for which these 500 MB are therefore significant. On the other hand, I don't see why proj should be required in that Docker container in the first place. Is proj meant to be a required dependency at the moment and would it be reasonable to change that?
Along similar lines, btw. vtk-devel requires e.g. Java, which I would rather see as an optional dependency. If one is developing for Java, one has Java installed, and others don't need that package.
Btw.: Thanks for the work on VTK and a happy new year!