CMake is not a great language, but great effort has been put into cleaning up how things should be done. However you can't just upgrade, someone needs to go through the effort of using all that new stuff. In almost all projects the build system is an after thought that developers touch as little as possible to make things work and so it builds cruft constantly.

You can do much better in CMake if you put some effort into cleaning it up - I have little hope anyone will do this though. We have a hard time getting developers to clean up messes in production code and that gets a lot more care and love.

I agree. Unless the project is huge, it's totally possible to use CMake in a maintainable way. It just requires some effort (not so much, but not nothing).