I think "letting this go" would be a mistake for one reason:
Wikileaks very, very likely has more emails.
They said they do. Jeff Weaver earlier today even noted that all the emails leaked only cover a small period of the primaries. And, I dunno, if I were trying to sabotage my opponent's elections, slowly leaking the emails over the course of their primary, thus guaranteeing it dominated the entire week, would make a whole lot of sense.
I do think this is something Dems need to stay ahead of like they did today.
Republicans aren't going to want to let this die.
Bernie holdouts aren't going to want to let this die.
The media won't want to let this die.
And Putin certainly won't want to let this die.
Tying this to Russia (and to Trump), makes this a much bigger deal than the DNC and provides a bit of cover.
I dunno, I guess we'll see how this week goes. But nobody should be surprised it this only the first email dump.