The e-mails contain details of strategic political planning on the part of the DNC, and although there doesn't seem to be much in the way of nefarious behavior described within, there is frank discussion of political strategy in dry terms that will damage the DNC's (and thus Hillary's) image even though this is how all political organizations operate. Unfortunately for Hillary, there is no RNC e-mail leak, so "this is how all political organizations work" won't be a sufficient defense in the wake of this leak and you can be assured that the conservative media is going to frame the content within these e-mails as cynically as possible. There is also the possibility that there is something legitimately damning yet to be uncovered.