In my opinion, voter registration is a reasonable regulation to protect everything I mentioned above, as long as it does not intimidate, discriminate, inconvenience, or harass citizens.

Historically, this is exactly what voter registration has been used for. You put it somewhere perpetually underfunded (especially in urban areas) like the DMV, and watch the results come in.

I don't disagree with the principle, but the current state of affairs makes it impossible to trust that voter registration laws are passed in good faith.

That's clearly not true, when the votes of California residents are worth significantly fewer electoral votes per capita than in any other state. Until the electoral college is replaced with a straight popular vote, we will never have the right to equally-weighted votes.

Correct.

The US Govt and many others already maintain a complete list of all persons, living and dead, including useful attributes like citizenship, current address, age (aka eligibility to vote), in real-time.

Maintaining separate, duplicate, opt-in, haphazardly maintained, patchwork voter registration databases is wasteful, error-prone, and only serves the purpose of disenfranchising undesirables.

Why should Federal government care who lives in Florida, aside from a population estimate for the Electoral College? That's Florida's business.

Maybe. Maybe voter rolls should be some sort of bio-token that proofs your uniqueness and existence, and your approximate location (to determine local eligibility) but uses a pseudonym and is not connected to anything like your taxes, drivers license, etc.