I have to concur with Mr. Crawford’s assessment that “it is always more complicated than one thinks.” One should not be too critical in these mattters because it’s unlikely one would do any better when one moves to the inside.
As far trying to influence the outcome by threatening your vote, I would say good luck on this particular activism. The power of your vote to effect the issue is very diluted. For starters, you are only given two choices: neither is great if one wants move the USA to the standards of other western countries. Using your vote in this way is only, at best, a nice platitude to rile up the fan base.
One of the best articles to describe American political/social forces is The New American Aristocracy. The political process works for these people. Either they have enough wealth to fund their own medical expenses OR they are able to select the better of the various insurance programs (and probably have some pull on the inside of the insurance companies).
When it comes to American health care, what the politicians are managing is just giving enough health coverage so as to not make it an election issue — while giving certain donors to campaigns the opportunity for more than enough profit. You see balancing act politicians have to play!
If you don’t like it, then it’s time to consider an alternative system to governance.