You make some good points, consider my counter-argument:
Voting is a formality, elections are a formality, etc. Democracy is also a formality. There have been many cases of kind autocrats who are loved by the people and who govern with their consent.
Many in the US are biased by the allure of democratic formalities and lose sight of the larger principle which is consent. Whether you vote or not, if you do not dissent then you consent to whatever is happening. This is true in any kind of regime, democratic or not.
I'd argue that it is the duty of all citizens to dissent aggressively when leaders act badly. This can take the form of voting behavior, public or private discourse, letter writing, fundraising, boycotting, civil disobedience, etc.
The contract between the people and their leaders should be reevaluated every hour of every day, not just viewed in retrospect after the 4 year term is over. Impeachment is an extreme measure, and too much of it is bad for the stability of our institutions, but the threat of it should be very real.
But just as stability is important for our institutions, so is trust. If the people cannot trust the president's words, that is just as large a threat to our stability as an impeachment proceeding.
We have granted our leaders the privilege of keeping some state secrets. They have taken that trust and created a massive surveillance infrastructure that goes well beyond what anyone imagined and well beyond the intent of the law. Now it is time to reduce the level of trust and dial back the excesses.
So far our leaders have shown no inclination to engage in a mutually respectful dialog with the public about the excesses (or about the crimes revealed by the leaks, for that matter). This conduct weakens our institutions more than most people realize. It is not only profoundly undemocratic, it is also profoundly disrespectful of the democracy that so many have fought to achieve.