You and I both see this the same way. Its my pet theory the Democratic Party isn't a "political party" as we know it, but a fragile coalition of various minority viewpoints. They are already a shrinking political "group" as the past decade has demonstrated. Not just with the loss of the House after four decades, but at the local and state levels. Membership is down, contributions aren't what McAufile suggested they would be four years ago.
In short, they can't afford to "offend" any single part of this "fragile coalition" mascarading as a viable political party in the traditional sense.
Which is why I think Gephardt is the only choice at the end of the day. He's not a trial lawyer, like Edwards, which would kill Kerry's rants about Health Care Costs. He's not a oil man ala Nunn, nor a warmonger as some on the left have viewed Nunn quietly out of camera and reporter range.
And Gephardt literally has nothing to lose at this point in his political career. Even if Kerry gets creamed in November, Gephardt would cement his stature for "fighting the good fight" and that plays well into his future as a leftwing lobbiest.
IMO, his best pick is Richardson. He's suffucuiently liberal so that he wouldn't offend the left wing and he brings along ethnic strength and also opens possibilities in the SW. In addition, he's currently outside of the Beltway. Although there's not a strong anti-incumbent mood this year, I think a ticket of a sitting US Senator and another Senator or Congressman is just to much of inside DC to play well across the country.