That'll work until the database of device credentials is breached from company X which provides call center support services for manufacturers A through Z and needs said credentials at hand.
Pretty much every home router sold in the UK is shipped with a unique default wifi network name and password printed on a sticker and stuck to the device.
Manufacturers don't need to keep a credential database, as legitimate users can simply look at the label.
Which gives the appearance of security, but do any of those routers have backdoors or superuser accounts with defaults or have access via remote management (TR-069?) that's not properly set-up? Should we shoot so low as just to get unique passwords?