Why is there a need for a 3rd party?
Are two choices always the answer? There are complicated questions out there and choice is always the answer.
It makes it easier to think that things come down to a right way or a wrong way. A right turn or a left turn. Should we really be thinking about government so simplistically? There is so much power that we yield to government and so many issues going on all the time that it is important to have many choices. It might make things seems a little more complicated than we are comfortable with but choice is what solves problems and presents us with a real ability to be involved and control what is happening around us.
People like to think that there is a variable scale of right and left but Libertarians do not view it so simply. We see a scale from no government to tyranny. The Libertarian philosophy is on the lower end of the scale near minimal but necessary government while Republicans and Democrats are racing to the other end with their own ideas of control over people. This means that a 3rd choice is actually critical for voters to have a voice to say they want less control and more freedom.
Even for those that do not necessarily agree with all of the Libertarian ideals, it is always important to have another option to say, "None of the above". Assuming that the Republicans or Democrats always provide candidates that give us a real option just doesn't make sense. Even core Republicans or Democrats sometimes need to make a 'protest' vote without outright voting for someone they disagree with completely.
There are many reason to have a 3rd party. Mostly it comes down you, as a voter, must seriously weigh your options and decide how to make your vote matter. A smart vote is a knowledgeable choice and part of being a responsible citizen..