You're ignorant of history. Yes, we'll have two parties due to our electoral system, but precisely which two parties can easily change. It's happened before. In fact, that's how the Republican party came to be. The Abolitionists spent nearly a century doing exactly what you advocate - voting for the lesser evil. Slavery only became more entrenched. It was only when they were willing to abandon the existing parties entirely and support a new third party - the Republicans, that Abolition actually happened.

We would have never had a President Lincoln if our ancestors had followed your advice.