Both my devices are rooted w/Cyanogenmod as it was easy for one (one-click installer) and I knew more for the other, I need access to install my custom Hosts file to block adds/Facebook, I also want a firewall, which you aren't getting without root (if there's a way, please let me know).
There are other capabilities that require root that I use regularly.
My devices came from Google, so weren't bloatware loaded thankfully, but having control to eliminate things that affect performance is required.
It's a tool for my use, not someone else's tool that I get to pay for and use for their purpose, thank you very much.
PS: LineageOS, the successor to CyanogenMod, is nearly up and running according to their latest blog post.