Those are good questions. Better email client would indeed be desirable. I am kinda surprised by the slowness of innovation in the space of email clients. I feel there is still a big opportunity in this area for some completely new product written from scratch...just nobody got it right yet.
I'm guessing that part of this would be the difficulty in getting the average corporate user to accept a radically different application. Even minor, release-to-release changes bother users--imagine what an entirely different interface might do.
