I would never treat my phone as my only copy of my data. I don't consider phone storage to be permanent OR a backup.
If you're into preserving your memories that are locked into your online services and apps like Google Photos, Facebook, Twitter, etc, I've started a project called Timeliner which downloads your data to your own home computers: https://github.com/mholt/timeliner - I run it on a cron every week.