This post from an anonymous Democrat, published a few days ago by Mark Halperin, is a pretty good summary of the case:
“Biden is deeply thoughtful, serious, passionate, experienced, highly knowledgeable, and incredibly sensible and clear when talking about major issues. He has a vast and creative understanding of politics and policy, a sharp mind, and a sincere heart. He’s totally ready to be president. Together, Obama and Biden would represent the best of the last 30 years of the Democratic Party, and the hope for the next 30.
Biden may be a ridiculous, overbearing blowhard, and he’ll doubtless make foolish blunders and imprudent comments if he’s on the ticket, but he’d still be an excellent campaigner, surrogate, and debater. He’d be thrilled at the prospect of being vice president (his own aspirations aside), and grateful and proud to have been chosenhe’d work hard to make Obama look good, and not deliberately outshine himplus the chemistry will be appealing, and they genuinely like and respect each other, which will be winningly apparent.
Also, America is no longer a place where citizens care about plagiarism or hair plugs. A Biden pick would immediately elevate Obama’s gravitas, give him a semblance of humility, delight the media, and reassure the nation that a grownup is involved. Democrats would be simultaneously relieved and apprehensive, but they’d be pleased with the choice overall. Plus, Biden is Catholic, is a Washington insider in a good way (a hardworking man of the people unchanged by three decades inside the Beltway), and has a tragic history with a happy ending.