Why create an instrument that has a limited upside, but a downside that can lead into totalitarianism, in the first place? If it does not exist, I don't need to trust anyone, hence there won't be a problem.

Institutions can go evil, as seen in any friendly dictatorship all over the world in the last 100+ year.

Keeping the police on the legal side of things seems to be challenging (ICE killings? Asset forfeiture? Police brutality?), better to make it harder for them to do something illegal in the first place.

I am still waiting on a working answer to the question of "who watches the watchmen", so far, this has never really worked (NSA/Snowden?). What has worked quite well was limiting the institutions up-front.