Yes some of the announcent are really out of hand. The Conductors make fine announcements, station stops and inform about delays. But the food cars make long, detailed, and many times unnecessary announcements. One time I heard the lounge car attendant explain how gambling is not permitted in the lounge and anyone playing cards is not allowed to have any money or items of value on the table. Really? The whole train needs to hear this and all of the other opinions of the lounge car attendant?
On the TE, there are very very often announcements about "don't walk barefoot" (yuck, like I would in the train cars) and about watching over your children and such. I remember once I was eating dinner with a man and his tween daughter, and the announcement about not walking barefoot came across, and she rolled her eyes and said, "They keep saying those things! Don't people LISTEN?!" and I kind of chuckled and said, "No, I don't think they do." (And both she and her father laughed).
But I do think there's a segment of the public that think "Da Rulez" don't apply to them, or that there's not a good reason for them, or perhaps they just don't listen. Also, I think sometimes now people are afraid of confronting people, so it's "easier" and perhaps safer to make a blanket "no gambling in the diner" announcement than it is to go up to the group of people breaking the rule and telling them to knock it off.
I see this as a larger and more general problem in society; at my place of work we regularly get e-mails "reminding" us to do things that 95% of us already do and would never think of NOT doing - it's because TPTB are either afraid of, or don't want to take the time to, confront that 5% directly, so instead, they nag at ALL of us. (It's not great for morale, I think). Or maybe they want a "paper trail" in case they have to initiate some kind of disciplinary procedure, I don't know.
But I agree - a lot of the "here are the rules" announcements seem to be made really often. I suppose that's because "common sense" is increasingly uncommon. (A lot of the rules - like not letting your kids run in the aisles and not walking barefoot, especially between cars - are just common sense)