At the end of the day, minimizing support costs for the vendor (not to mention likely annoyance for the customer) trumps providing "default" security for the folks who won't change the default password.
The MyFi apparently does this. According to http://www.nytimes.com/2009/05/07/technology/personaltech/07pogue.html"The network password is printed right there on the bottom of the MiFi itself."
At least it's not "0000".
But yes, my Mifi *had* the password on the bottom.
In a lot of cases, physical access = you're screwed anyway. What's the difference if the password is printed on the box? If you can't physically protect your kit, that's something else, but aside from things like WAP's which are routinely in 'the open' surely you protect your equipment inside secure racks/cabinets/datacentres such that the physical labelling is inaccessible to those who aren't authorised... ?