"Republicunt": why use terms like this?

[Ravenshire]

The trouble is by being republican they sign up for certain things. its like being a member of the Klu Klux Klan.
Sure they may think themselves as nice and all but they are still members of the Klu Klux Klan.
The republican party of today has been on a right wing trajectory for a while now and by being a "republican" you identify with policies that Goebels would find a bit much.
It bears little resemblance to the party even of Reagan which was pretty right wing compared to UK politics then and now.

You don't sign up for anything by being republican other than being able to vote in republican primaries.  There are a limited number of political options, all with significant shortcomings.  Because of the way candidates are nominated, it is often impractical to be labeled an independent.  So republican or democrat are usually it.  

Similarly, when you are faced with two candidates, voting for one doesn't endorse everything that candidate did.  It is only picking that person over the alternative.  Often weighing a number of pluses and negatives.  Again, the alternative of just nobody voting isn't practical.

Contrast with joining the Klu Klux Klan, you can just not join them.  With that, because there's no need to join the KKK, there is likely a stronger endorsement of the behaviors of the KKK.

You need to start a campaign to get your state to allow independents to vote in the Democratic and Republican primaries. That opens all the parties as relevant choices.