I think you’re overstating the meaning of registering as independent/non-affiliated. While the number of people who are not registering as part of a party has grown, most still vote straight party-line tickets and are not really different from registered Democrats or Republicans.
This is a tautological argument. My point is that too great a percentage of the electorate is motivated by fear. Too many people get browbeaten into voting for the major party candidates because every other so-called expert in the media is trying to invalidate their decision to vote for someone else. The social pressure to choose the so-called lesser of two evils is enormous.
I am here to encourage people to vote for someone else, to tell them it’s OK, and it’s actually the moral thing to do, while voting for Clinton or Trump is an immoral act. Unequivocally. So, yes, maybe many of them — perhaps even a majority — vote straight party-line tickets today, but you will see less straight party-line voting in a world of diminishing Democratic and Republican influence, which is precisely what a mass movement of people not joining either of those parties or voting for either of their terrible candidates accomplishes.
Every vote for someone besides Trump or Clinton matters. Every vote inches the country a tiny bit closer to getting out from under this corrupt system and encourages more people to do the same.
The biggest problem with the idea that a vote for a third-party presidential candidate will bring major change is that without allies in Congress and statehouses, a third-party president will be effectively blocked from making major changes. They can do a lot administratively, but fundamental, lasting changes are unlikely. Third-party presidential candidates are valuable for raising ideas and gaining attention, but if these parties really want to be relevant, they need strong candidates at the state and local level who can then credibly compete for Congressional seats.
Isn’t this already a problem. Don’t Obama apologists blame the obstructionist Congress for all of his shortcomings as President? Which Republicans are lining up to work with Clinton? Which Democrats are going to work with Trump? Is anybody going to work with Trump? Who is really going to do anything that doesn’t get the approval of the oligarch class that has bought virtually every vote in Congress?
But, yes, there should be higher third-party and Independent representation in Congress as well. If the Democratic and Republican parties keep shrinking as a percentage of the voting public, which will snowball off of every vote that goes to someone else in the general election, that would seem to be inevitable, wouldn’t it? In some districts, it’s far easier for an Independent or third-party candidate to win than it is at the national level.