While certainly for large teams it makes sense for people to specialize, and for you're hard core programmers to not also handle the visual design.
However, I think it's a cop out to claim them to be so totally different and "asking a coder to do artwork is silly".
I work with many people who are excellent coders and who are also excellent designers. In fact, some of the best programmers I know are also artists (painters, photographers or musicians) and can do excellent web and UI design.
So, if you're a coder who can't do art, that's fine. But if you are a coder who can't do art who wants to, don't let these guys discourage you.
And to Microsoft, the more tools the better. Maybe one will actually be good.