Here's the thing:
If enough people vote 3rd party, and a two-party candidate loses because of it, some majorly bad things will happen to the said party. They will recognize that a significant amount of voters are dissatisifed with the platform.
They will have to do one of two things:
1) Adopt the 3rd parties' platform in some areas to cater
2) Cede that the party has become irrelevant (Whigs), resulting in the 3rd party becoming a major party
3) Keep fighting, and become a 3rd party themselves.
Its worth it to vote 3rd party, because of any vote, it sends a message. It tells the politicians that they've screwed up. This has happened in both parties when long standing incumbents have been voted out. That's a start, but it needs to end in more parties being on the table. In Ohio, we had 3rd party candidates receive 5% of the vote in many races. That is a good start. But if it continues, it'll end up destroying the 2 party system.
Back from the dead, I'm afraid.
