Perhaps I'm misinterpreting. But I got the impression that dev tools that qualify to be sent out into the world need to have a primary emphasis on friendliness, automation and autogeneration, and general polish. By contrast, internal tools need to be industrial grade workhorses, and if you can improve them by putting a better interface on them, that's merely nice. One of the clearest examples I can think of is the difference between their internal workhorse Source Depot and their public tool TFS (nevermind the horror that was VSS).

Like I said, I might be misreading things. And certainly the blogging community around their dev tools has improved the level of detail that goes out to developers committed enough to keep up with them.