Necessary is a matter of perspective, and what it is you need your device to do. Mine is that if you don’t have root (or equivalent) on a computer, you don’t really own it. That’s a philosophical point more than a practical one - I’d want root even if I didn’t currently have a use for it.
Practically, here are some things I use root for in 2023:
Advanced charge controller - limit battery charge to extend service life. Some devices have a built-in option now, but it’s usually only a single switch for 85%. I usually set it to 60%.
Backup of apps with their data (Neo Backup), to install onto another device or after a factory reset - I don’t think there’s a way to do anything like this without root.
Mounting remote devices for access by arbitrary apps using EasySSHFS - I don’t think there’s a good equivalent.
Accessing exfat format external drives, like the SD cards in my camera using MiXPlorer’s built-in filesystem drivers. Android is an asshole for not supporting more filesystems. It’s Linux; the support already exists.
Hosts file ad blocking - DNS ad blocking is a viable alternative now.
If something blocks me from using it with root, I’ll give it a 1-star review on Google Play and probably not use it even if I can get around the blocking. If my bank starts using more effective blocking, I will probably change banks.