The problem is that other sources are not willing to perform the kinds of investigations and do the sort of publications Wikileaks and few others are willing to do.

When Snowden approached CNN, the Times and a number of other large media outlets they attempted to report him to the Feds rather than report on the domestic and global mass surveillance programmes.

The incentives, partnerships, timelines and ethics of major media outlets prevent them from speaking truth to power.

If the story was incomplete do you honestly believe we wouldnt find that out? I dont.

EDIT:

1) Wikileaks provides evidence of wrongdoing

2) You respond "Its possible evidence that proves this isnt wrongdoing exists"

Your position seems to be roughly meaningless and the only justification I see to take it on is ideological.

It's plausible that WL is selectively holding back documents on e.g. Russian activities in Syria. No one would have the power and incentive to leak those documents separately, so WL could portray an incomplete story.

It's not plausible that WL unfairly portrayed Podesta and the DNC by incomplete leaking. The leak targets have both the power and incentive to clarify any serious misrepresentation by releasing the context they already possess.

Somehow, I keep seeing people give the Syria example, then claim that we should disregard even the US-domestic leaks because "there could be context we don't have!" It doesn't make much more sense than saying "sure, the murder suspect didn't offer any defense, but maybe he has an alibi he never bothered to mention!"

The CIA could surely filll in the gaps if they wanted to, at the very least through leaks to any of the media organizations that would like to see them succeed.