This. This is the biggest, worst oversight in Android.
This past weekend I spent a very long time grappling with a family android device that had what I presume is a software fault causing the wifi not to work very well.
I wanted to backup everything, do a factory reset, check it worked in its vanilla condition then restore everything. What a fucking nightmare.
In addition to having no native way to do a full backup to an SD card or to a local computer, none of the apps that purport to do this actual work worth a damn and most of them are usability nightmares. It's absolutely inexcusable that the only native backup facility android has is to backup user data to google's cloud services. Backup to SD full app data (APK plus created files) should be a no-brainer, but it'd be really nice if Google at least had some sort of Chrome extension that stored backups on a local computer via USB.