Well, while they do, at least it keeps me in a bit of a pocket money job sorting out wireless security for people! Seriously though, the likes of BT have it right, they provide their wireless routers with a random hexadecimal WPA key printed on the bottom of the router. Perfect, you never need to change it and it's always there in case you need to re-input the key at any point.
It's perfect for home use, as it's obviously intended for, which means the wireless is never left open by default to allow someone to compromise it.
Technology in general is sold to the masses without proper instructions. As you say, hardware manufacturers are to blame. Mind you, I have found it a godsend sometimes when netgear routers are unencrypted by default, especially when you go to someone's house to install a new one for them and you forget to take a LAN cable!! So they can't win, really
Still think BT have the best idea (and it's not often you'll hear me say that about BT!!)