I think that it is important to ensure a valid Democratic Process, that we allow third party candidates to be on the ballot in each state. Not only that, I think that they should be represented during presidential debates. Currently, too many people are voting for the lesser of two evils, as opposed to voting for the candidate that is the best.
Our constitution said that human beings have 3 basic rights. The right to life, the right to liberty, and the right of pursuit of happiness. Without 3rd party Presidential candidates appearing we are negating their right to pursuit of happiness, which would come in the form of them being recognized as running for president.
Yes, they should always be included. An election isn't complete unless all of the possibilities are presented to the voters. Do I expect they would win? No, not generally, but that doesn't matter. If a person is a candidate for a position, their names should be on the ballot. It only makes sense. If they aren't on the ballot, then their candidacy doesn't really count, does it?
I believe that third party presidential candidates should appear on the ballot in every state so that voters have additional choices outside of the primary two parties. I think that a two-party system significantly reduces the potential for creativity and problem solving, whereas third and fourth parties would allow for non-traditional ideas and unique solutions to the many problems our country faces.
These are not two-person elections, no matter what the media may tell you to the contrary. There are SEVERAL other deserving, if not more deserving, candidates than the main two we are given each election. Third party candidates running for President ought to get the same chance to win as the big guys do. It isn't fair that because they aren't big names or part of the big two parties, they are effectively shut out from the public. It should be a level playing field, they deserve a fair shake.