Many Democratic women believe Clinton deserves the 2016 nomination because she was a graceful loser in 2008 and a good soldier thereafter. Nonetheless, having Clinton and Warren debate Democratic principles would be good for the party. However, the most serious problem with a Clinton-Warren battle is not gender or ideology. It's money. Many Democrats believe that having Clinton as their presidential candidate would ensure that Dems would receive millions in Wall Street donations, and enough campaign funds in general, to triumph over any likely Republican candidate.
Rather than being devoted to finding the best policy alternative, the divisions of party leave us to pursue only the second or third best alternative, usually the one that gives the least amount of credit to the other side. It is a downward spiral toward ever more narrow and inflexible partisanly limited options.