The era of rampant, selective intelligence leaks to the media started when these very same people were in administration.
The only real secret intelligence is tactical (military or otherwise), because we aren't quite that craven, exceptions notwithstanding. Everything else is intrinsically political and has a very short half-life as a secret. Work for a few years inside the Beltway, especially with or near people who are connected (e.g. lobbyists, think tank scholars, appointees, Pentagon staffers, international orgs, etc), and this becomes obvious immediately. Secrets are social currency more important than money and maybe even title. Everybody shares secrets, albeit usually in an obnoxious, obfuscated, pretentious way; even the interns.
I think you are conflating a few issues.
On the one hand there is the bipartisan surveillance issue that Snowden shined a light on.
More recently we have a bunch of Trump and anti-Trump narratives and sometimes conspiracy theories.
I suspect some people on the thread have squished those into one. But the intelligence community is likely complicated, motivations multi-faceted, people holding diverse opinions. I don't think these things are the same, or you can dismiss or endorse one cause for the other.
2) CNN and MSNBC absolutely are partisan entities, though CNN does try hard to appear less so. As long as MSNBC keeps employing Maddow and she keeps pushing debunked conspiracy theories, they will absolutely be seen as partisan. Her coverage as of late has been absolutely disgraceful and a huge stain on that network, IMO.
3) None of what you said addresses the very alarming fact that the heads of our intelligence agencies are taking senior posts in these media organizations.
If it weren't partisan politics, you wouldn't be seeing roughly 15 senior officials from the NSA/CIA/FBI leaving the public sector to take jobs at CNN & MSNBC.
I'm curious why most people don't find this to be deeply disturbing.