You don’t have to. I worked on data analysis (mostly cleaning and correction) for CMS (one of the two main experiments at LHC) for a while and didn’t have to touch it. Disclaimer: I was a high energy theorist, but did the aforementioned experimental work early in my PhD for funding.

I did my master and PhD around the time numpy/scipy got competitive for a lot of analysis (for me a complete replacement) but the Python binding for root weren't there or in beta. Root-the-data+format remained however the main output of Geant4, so I set up a tiny Python wrapper around a root script that would dump any .root contents and load it up in a numpy file.

My plots looked a lot nicer ;)

These days you can mostly avoid it. The Python HEP ecosystem is now pretty advanced so you can even read ROOT files without needing root itself. See:

https://scikit-hep.org/

ROOT 7 is coming. Things are being discussed this year about it, the target is for HL-LHC. See link below. https://indico.cern.ch/event/1369601/contributions/5867782/a...