My organization has created a number of apps and maps in ArcGIS online, and our stakeholders wanted the peace of mind that if the ArcGIS site was compromised and our content was corrupted (or there was user error and the apps/maps were deleted / altered), we'd be able to restore everything based on a backup of the ArcGIS online content, and the downtime of our public app would be minimal.
Currently, there is an option to download maps, and some apps (one at a time) to the desktop version, but not all app templates are available for download (in our case, Story Map Journals, Story Map Cascades and Story Map Series apps are not available for download).
The apps are where the majority of our development hours went into (connecting and customizing the maps into the apps), and if this content were lost, it would take a few weeks to get our public site operational again, which is a huge organizational risk.
This idea is to have all Apps and Maps be available for local back up (they do not all need to be editable in ArcMap or local Esri products, just a backup to allow for a restore of ArcGIS Online), and to have a bulk backup option, so content doesn't need to be downloaded one at a time. This included all of the map connections and customizations made within the apps.
This suggestion has been logged under Enhancement Number ENH-000107517, this idea is to promote the concept to other users to get further buy-in and get the idea promoted into development state.