We always have done! Attacks, prejudice and antisocial behaviour are no more common now than they were 20 or 30 years ago yet back then the idea you'd have to sit through five minutes of warnings and instructions every time your train called at a station would have been laughable.
That is considerable hyperbole.
On many routes you don't even get that sort of announcement at a stop, let alone something that long. If it bothers you so much, I suggest buying some noise-cancelling headphones.