The Worldmode devices are significantly different to a standard GSM handset in the sense that first and foremost, they're sold as CDMA devices to connect to a CDMA network. They only connect to a GSM network when there is no CDMA network available. Yes they can be unlocked, but they're intended for use by travelers and people who want their phones "to just work". Could I argue that this is protecting the customer experience, too? Also, are you sure they're sold unsubsidised?
I doubt that we'll ever see the Telecom Worldmode devices unlocked, either - mainly because they won't work on the new network currently being built out. By the time the CDMA network closes, I would think that most - if not all - customers would have upgraded anyway.