The problem is that if the candidate from Party "A" is a competent weasel who wants to undermine everything I stand for, and party "B"'s candidate is an incompetent boob who won't help matters but also is popular and won't actively ruin everything, then it's far more important to my interests that party "A"'s candidate not be voted in than it is to cast a vote for candidate "C". The system is working how is designed to and the only people who are capable of changing it are the ones benefiting from it being broken, so the only way that's likely to happen is if there were somehow a mass exodus away from the big two parties.