Over the years, I find rooting less useful. In the early Android days, root was needed for backup/restore, screen shots, over/under clocking, ROMs, disabling useless apps and installing modules for xposed.
Screenshot is built into the OS so no need for that.
Backup/restore, most phones have their own built in backup/restore.
Over/underclocking isn't useful and more issues then anything now.
Stocks ROMs now as just as good as modified ROMs and gain is little.
Disabling useless apps is possible in Android KK and higher.
Installing modules is not needed unless you are just messing around now.
Root is to gain Superuser access.
Unlocking the bootloader pretty much sets your phone free and you can do anything you want like ROMs, root, nandroid backups and so on.
Unlocking the phone is pretty much carrier unrestricted.