ADB is also much less flexible. I have Titanium Backup making nightly backups, and then FolderSync automatically pushes them to a SFTP server I run. If something should happen to my phone, I'll lose one day of data. This is all automatic, so I don't have to think about it. A backup like ADB that requires manual intervention is likely to be only done irregularly, and Murphy says that you'll lose your phone just after forgetting to make a backup for weeks. Being able to do this is the only reason I bother to root my Android.