Thanks for your words!
I don’t think dropping the Python dependency completely is a wise move especially that by IO, I also mean the simple visualization and rendering aspect which I think is best left to VTK. For instance, direct visualization of files might be something of use, in which case there is no need to go from Julia to VTK, it can all be done in VTK.
However, making readers and writers purely in Julia certainly seems like the right way of doing things especially that it is mostly just reading and writing XML files for which there are tools in Julia. I am presonally not so much of a purist myself, so I wouldn’t go too far just to get rid of the Python dependency but any pull request that doesn’t mess with the remaining use cases is certainly more than welcome 
Btw VTK is also used for writing vtp files which WriteVTK doesn’t support. I also adapted the vtm and pvd writing codes from WriteVTK to enable them to reference other vtp files, so the dependency is quite rooted in the reading and writing code.