This is negligence to the extreme. I wouldn't be surprised to see manslaughter charges against someone. If you are using real bullets in a prop gun that will be aimed at people, leaving bullets in it is severe recklessness.
The armorer is a 24 year old female that got the job because her father was a famous armorer. She was not qualified. It has also been reported that multiple armorers turned down the gig because of the low pay, so they hired an unexperienced person.
Most armorers own all the firearms themselves. They know the quality, condition, and they control them, keeping them locked up when not being used on set. They should be locked up when not being filmed, and only handed from the armorer to the actor and immediately back. Even blanks can be dangerous due to the pressure, so the armorer must supervise to ensure proper distances are kept, and barrels aren't actually pointed at people. Actors are also supposed to have live fire training on the guns, so they have respect for them, and understand gun safety. I'm not sure if that occurred on this film.
I'll reiterate what I said above, no qualified armorer would ever let a set firearm be used for target practice between sets. That is just insane, and sadly it ended in a life.
It is unclear if Baldwin is the producer or just an executive producer, which many actors get the title for prestige, but don't have much if any control over the set. If he was the producer, and he let all of this occur, at a minimum, he should be financially liable, although I'm sure they have insurance on set.
It will not be surprising to see criminal charges.
I don't see an issue with using blanks if you have proper controls, which 99.99% of other movies do have. The cost for CGI add-in can be prohibitive, and like CGI generally, won't look as good as the real thing. I expect that even if CA bans blanks, other states will still allow it and it will still occur, hopefully with even better safety.