My guess is that manufacturers will just add an initial-setup subroutine that won't allow setup to proceed until the default password is changed by the person doing the work.
One issue with requiring each and every bit of hardware to have a unique password will be more e-waste if these devices are less useful on the secondary market. A common technique to work with old hardware is to perform a factory reset on the bench before reconfiguring it for one's own purposes.
Then again, since most devices, even cheap devices, have their MAC addresses printed on them, it wouldn't be all that difficult to populate the same table used for that with the factory unique password in the printing system, and to then include that unique password on the label. It would still be a good idea to force the user to change the password, but if they don't then it would at least require someone to have gained physical access to the device in order to get that password. I suppose a dictionary attack could be used if the vendor password list leaked to the Internet as well, but that's a whole new level of failure.