Comment by yannyu

AT&T routers, for example, ship like this. There's a wifi network and a wifi password printed onto the device.

But that also means then that often anyone with physical access can easily get into the device. The complicated password provides an additional layer of illusion of security, because people then figure "it's not a default admin password, it should be good". The fundamental problem seems to be "many people are bad at passwords and onboarding flows", and so trying variations on shipping passwords seem to result in mostly the same problems.