I wasn't really sure if it's useful for anything and I never got an definitive answer but it's pretty cool for sure.
However in the last 7 years some things in DokuWiki changed and the script no longer worked. And people actually complained about it. So on a recent train journey I took the time to bring it up to more modern standards.
You can download an up-to-date version at github.
Please note that this is not a DokuWiki plugin, so you can't install it with the extension manager. I sometimes think about making command line scripts a new plugin type. When I do that, I'll update the grapher to be installable as real plugin.