Why don't they want everyone buying a cingular phone? Think about it. Of the Treos released:

Sprint: Locked.
AT&T: Locked.
Cingular: Unlocked.
Generic: Unlocked, but not available in US.

Now if EVERYONE starts buying the cingular version to use on other networks, this is seriously going to play havoc with their numbers? It's not just the number of sales, it's the number of sales to particular carriers. What if AT&T and TMOBILE start saying to themselves: "Gee. This stupid thing isn't selling as well as we thought it would" because people are sidestepping the subsidy lock and buying cingular units?