Sadly, this is very much the culture we've created over the last ten years or so. I remember going to Hong Kong years ago and noticing this. Escalators telling you to hold onto the handrail, shopping malls pointing out where the fire exits were.
Here's catching up sadly and the railway is one of the standard-bearers for it. You can't sit in Liverpool Lime Street for more than five minutes without being lectured about unattended luggage etc by a patronizing female voice (it's nearly always female and it's nearly always patronizing). The only announcements routinely needed are for whatever train is leaving, where it is going and what platform it is leaving at. This thing of name-checking every station it calls at, as if we're all too retarded to figure that out for ourselves, is another annoying trend.
As for onboard trains, again, an announcement when approaching the next station is all that's needed. No rubbish about leaving your false teeth in when you sleep etc.
Anyone ever been on the Mersey Ferries in recent years? They now have this long-winded announcement by someone who sounds exactly like Ringo Starr (who knows, could be him) which goes on for at least three minutes or so. It rambles on about emergency situations, how a single horn will sound in one set of circumstances and two horns will sound in another situation etc. It's irritating upon the first time of hearing it. Some people actually commute on these ferries. Assuming the do five return journeys a week, they here it ten times per week, approximately forty times a month. I wouldn't be surprised if it puts people off using them.
All in all, some announcements are useful, but let's cut the hyperbole.
