Yeah, while Biden was Obama's V.P. for 8 years they didn't want to criticize him, despite the abundant creepy examples on video being out there all that time.

Now that Biden is one of many 2020 potential primary candidates, the liberal media want to knock him out of the running to make room for someone less white and more "progressive" (i.e., far-left).
The fact that Biden is the highest-polling by far in the Democrat field speaks of how lackluster the Democrat primary field is. Kicking Biden down won't make any of these maniacs any more electable.

Corey Booker, Elizabeth "Pocahantas" Warren, Kamala Harris, all the rest, are in the very low single digits. The only other that even comes close to Biden is Bernie Sanders, another 77 year old white guy.
And I'd lay money that the same group unleashing these attacks on Biden will have the long knives out for Sanders once Biden is knocked out of the running.