Voting for a major party candidate does not matter, since both major parties strongly support the status quo. I'd say 80% of the power structure influencing US politics strongly agrees with the status quo. It follows that anyone who can get elected president has essentially promised to continue the status quo.
However, I do think that voting for 3rd party candiates could help over time. If even 10% of Americans voted for a 3rd party candidate in a presidential election, things would start to change. If there were two viable 3rd party candidates things would change faster.
It seems that the 50% of eligible citizens who choose to vote very much prefer to vote for a major party candidate. This goes along with the general herd behavior of animals like us, and also makes sense in light of the massive amplification of differences between the parties. So much money is spent to magnify (and dignify) the smallest differences between candidates/parties so that the average person can come to think that his/her vote for one of those parties (and for the status quo) mattered.
The main reason we don't have much dissent is because of the vast efforts by the powerful and the media to focus on the delegitimization of nearly all institutions other than the US Government. NPR will cover nearly any story but never ask questions about the trustworthiness or legitimacy of any part of the US Government.
The occupy movement helps disempower private institutions, the NY Times stories about China flooding helps alienate us from other humans who live in China. And the presentation of the third world is much, much worse. There is a massive bias toward government institutions over private ones... Occupy is nowhere near as hard on the corrupt regulators as it is on the firms. All this helps squash dissent.
The Intercept seems to be one of the first efforts to offer the mainstream media consumer an alternative view. The internet has (so far) made it easier for powerful interests to shape opinion, but that may start to change as groups like The Intercept have the budget to do the kind of high quality reporting that can be tough to ignore.
But with so much money riding on continuation of the status quo, there will always be lots of influential people (academics, politicians, pundits, business leaders) who will completely ignore things like this in favor of focusing on one of the many silly issues covered by mainstream television and newspapers. As a case in point, Zuckerberg would absolutely never make a public statement supporting this reporting, since his interests are already quite closely tied to continuing the status quo. Similarly, Bezos now owns the WaPo but would never syndicate this coverage.
So more than voting, the issue is lack of dissent.
As an aside, the most telling aspect of this is when the US president suffers through a (very rare) interview. The journalist simply will not ask tough questions and the atmosphere is one of utter groveling and supplication. Of all things, I can't believe we are willing to live in a society where this happens... but it's considered such a rare honor to do a one hour on-on-one with a president that of course only the most ingratiating journalist (if one can call them that) would ever get the chance.