I think they fear that the Republicans are simply biding their time with Hillary, in terms of taking her down at the moment of their choosing. That is, when it would too late for the Democrats to proffer a strong alternative in her place. Therefore, if Hillary is going to go down anyway, they (the MSM) want to see it happen sooner rather than later. That way they’d have time to prop someone else up (such as Elizabeth Warren) and basically carry that someone across the finish line like they have done twice now with Obama.