I also said a lot of other things, all of which you appear to have ignored.
The problem is that I don’t think you are entirely sure how the constitution works or why.
Specifically; if someone makes a law somewhere, or challenges someone’s actions; there has to be some method by which who is right can be determine.
This is called the court system.
To be absolutely fair, in federal matters, there is a process of appeals, and a system in place to allow challenges so that one judge is not solely responsible for far-reaching decisions.
This is the federal circuit and appeal process.
The appeals cannot go on forever: so for any legal challenge there needs to be a final level at which a ruling can be appealed.
This is the Supreme Court.
In any system of government, at all, in any way shape or form; you need someone at that final level of appeal: someone who is able to decide which side is valid.
If voters pass a rule that violates some explicit part of the constitution - who exactly would decide that?
Imagine that judges are now only allowed to invalidate lass that are explicitly part of the constitution.
If that judge overstepped and decided that something was against the constitution - but it wasn’t: who would make that determination?
If you gave the decision to someone else, what’s to stop them making a bad decision?
The fundamental error you make, is you are operating under the premise that a system of laws in a democracy can operate without ultimately falling down to some partisan making decisions.
If things were solely down to democratic votes; then the people who decide what the constitution means are politicians, and the constitution means whatever the people can be convinced it means.
To make sure the laws are stable, you ideally want arbiters that are as impartial as possible. That generally mean lifetime appointments - because you don’t want judgements based on what keeps you popular as opposed to are correct.
You want elected representatives to chose and have the ability to remove if necessary these judges.
Finally, to make sure that what the constitution means, and what the overall law of the land cannot be overridden by a simply majority When one side sweeps power, you want to make fundamental changes, and the ability to purge political roadblocks to be hard to do just by winning a majority of votes.
All of those things are true in the current system.
The ruling made on Prop 187 went to federal court where it was decided based on existing common law precedent that the federal government sets immigration law. It was going through the court system when Gray Davis won a state wide democratic election - and pulled the challenge to the case - essentially removing people 187.
So the democratically elected governor was responsible for subverting the will of the people.
If it has gone on, and was upheld; then the reason it would have failed - despite having the public vote for it - was that the publicly voted for a law was itself not legal as per the understood precedents of common law.
Because immigration is under federal control, in order to keep consistent rules across all states - then the people of California did not have the power to make that determination. Instead they needed to get together with a majority of other states and pass federal law (rather than state law) to make it happen.