It doesn't make Hersh right (I don't know if he is or not), but I do know that a common response to outsiders who challenge insiders is to attack their character. It's a way of creating FUD and of deterring others.
So either the media has to admit that they, as a whole, massively screwed up the story (not unlike the WMD stuff) or they can just attack Hersh and not seem to lose any credibility.
In other words, it's in their best interest he's wrong even if he's right. It was a very good interview.
I don't think this is entirely fair, if he's referring to media coverage in the years before his piece. Only a small number of intelligence and military officials across the world know the truth about the operation. Any US, or likely even Pakistani, officials interviewed by the media would likely have corroborated the Obama administraiton's original story. Without a high-level leaker, there isn't a lot the media could have done.
It's a different story for how the media handles things in the face of Hersh's expose, though.
Sorry my memory is failing me. The basic point is he did make it seem like they were threads the media could've pulled at to at least give the administration story a bit more of a skeptical eye.
But even for them, attacking a very distinguished journalist's character, instead of analyzing his work on it's merit is new low.
They may be uneducated or gullible or lacking the will to question preprocessed information... But likely sane.
This is not a new development. What's new is he availability of no -mainstream reporting.
https://firstlook.org/theintercept/2014/09/25/managing-night...
(I haven't read it closely enough to say how much I believe it myself.)