Because it's not to the point of putting in on the front page? The tool used to do this is in a barely functional state as it is, and aside from this, you lose many capabilities on your phone. Surely losing the ability to sync with iTunes is a show-stopper, non? It'll be all over the Internet when there's something halfway usable for the general public, that's for certain.
About on par with this
response. For these reasons I can't wait for the day that I can do this with my iPhone. It'll be my personal payback for making MobileMail.app the bastardised in-bred child of Mail.app.