"I'd say you say something to the airline, it's the crew's job (not yours) to deal with them if they're ignoring the rules and possibly endangering people."

Yes, and then the people complain to the airline with a complaint taken out of context (similar sometimes to what can happen here) and they get reprimanded.

Raise any concern you want to the airplane staff. It gives them the onus to approach the passengers. This is especially true up front where so many people their the sun shines out of their backside and the rules don't apply to them. Complain and they'll be able to do something.

"Just listening to the PA announcements makes me feel like I'm stuck in some sort of Orwell/Bradbury nightmare, "If you see anyone acting suspicious, please inform a TSA representative.""

No, you just needed to spend some time in the UK when there were worries about IRA attacks. Everyone was looking around for anyone leaving a bag on anything. It's not orwellian. It's just a precaution. It's not like you're peering in through anyone's window and when's the last time anyone you know ever felt the need to report someone at the airport.

If people are doing things unsafe in the air and reducing your level of personal safety then call them on it. It's a much easier situation to handle if other passengers are complaining.