Bah, in our media saturated country, they should be able to get all the coverage they want, if only people were interested in hearing them. There is no shortage of outlets and networks are very interested in finding content...if it will draw viewership.
The fact is that the minor parties tend to be sub-par. A talented libertarian would do better as a libertarian/Republican rather than as a libertarian. Likewise, there's plenty of room for environmentalists in the Democratic party. The third parties are for people with fringe beliefs. Smaller fishbowls for smaller fish. Ron Paul was a Libertarian, and secured a House seat. Rand Paul became a Libertarian/Republican and became a Senator. The Libertarian party was too small for someone of even Rand Paul's meagre talents. Both the Green and Libertarian parties are riddled with conspiracy theorists, and others who have a reason for not going with the major parties. Sure, disgust at the status quo is something, but the idea that these fringe parties are more capable of changing the status quo than someone working within the system is fatuous. One of the biggest conspiracy theories is the idea that 'the media' is out to block people out. 'The Media' will put anything on that generates revenue. Johnson and Stein are not being excluded because they aren't part of the major parties; they are being excluded because no one is interested in watching them.
Johnson and Stein are fools. The idea that exposing them to a wider audience would bring them more support is foolish. They've both gotten media coverage, and both have failed to parlay that into a major following. If the coverage they got had been found interesting, then their coverage would have increased.