My lingering reason(s) to root has only intensified in the years since Android Gingerbread.
System-wide adblocking, to not waste data and battery on loading digital herpes. I don't care how much the makers are getting paid; I don't care if they are willing to pay ME directly. The problem is the ads are often vectors for malware and compromise a system or phone faster than literal viruses nowadays.
Clean/Sanitized ROMs to run on the phone. Even as far back as the Galaxy S3, optimized community roms often got me far better battery life than any factory rom. Having Lineage on my LG v20 allowed me to miss all of the LG IMS soft-bricking mess that was going on with T-Mobile for a while there. And with my present phone, even though I explicitly bought it as retail unlocked to avoid any carrier nonsense, it still forces me to do system updates just like a carrier locked phone.
More recently, because of Google using DMCA against YouTube Vanced, there was then the project of ReVanced where they got around that by just making the end user build the patched apk. Well, the android app that would do that for the programs it supports will not let me install a built apk unless it's a rooted phone! So that just hosed any plans of keeping my phone at least away from ads as much as possible.