Hillary probably didn’t do it because shes not very likeable, it would have been another Jeb Bush style mistake. Jeb made himself look worse, so sometimes not bothering is the lesser hurt. Hillary is a long way from her husband in that regard when he was at his peak. Bernie would make it work, that’s obvious, but then he would never had not done it.

The problem is that you don’t just need one thing, you need as many things as you can get, and what you certainly do not need is your own party’s management working against you. Winning when they cut you off becomes very difficult as you lose the biggest funding hose.