Too many generic announcements are actually harmful, as passengers switch off and stop paying attention. Then, when there's actually something important being said, the pax are more likely to miss out on it.
Far better in my view to have only essential information audibly announced, which is realistically only two things: booked stops and during delays. All that bumf about penalty fares etc can go on the scrolling information screens or posters for people to read at their own leisure.
In normal running many announcements are indeed pointless (if not of any benefit to those that need them, such as the blind, such as ones to say smoking isn't allowed, keep bags with you etc).
However, during disruption I really don't see that the argument is valid anymore. People can by all means switch off, but not everyone will and will gladly appreciate information and updates.
As said above, being told of residual delays is also beneficial - as it tells me that I might have to wait, but the problem is over. Once I get on a train (or we get moving if already on it), chances are I'll suffer no more delays.
If there's an ongoing incident and nobody can tell me what's happening, I have no idea if I'm on there for 30 minutes more, an hour, two hours...
This is one case where the railway could do with copying the airlines - though I do realise that an airline captain has easy access to a lot more information than a member of train staff.
On a flight some time ago, they announced before take-off there would be a delay due to one of the flight deck radios not working and there was a technician on the way with a replacement. There may even have been some mention of international safety regulations requiring all radios to be working before takeoff. They expected the delay to be about an hour. Sure enough about 20min later a bloke in overalls turned up with a box of electronics and the total delay turned out to be somewhat less than an hour.
This shows passengers that the company is on top of the problem, it's the sort of problem passengers can relate to (we all know electronics goes on the blink and we wouldn't want to fly without a working radio) and that the amount of delay is known. It's always better to slightly exaggerate the likely delay both to provide a margin for unforeseen circumstances and because people feel happier when it turns out to be not quite as bad as they feared.
All the above still applies even if the radio fault was caused by the company cancelling the maintenance contract to save money...
If this had been explaned as a non-specific technical fault then everybody would have been worrying not only about the length of delay but also what was at fault and whether things were truly going to be safe when the flight took off.
A good explanation is a way of letting people know the problem was caused by someone else (especially if it's someone outside the railway - see post above re passenger alarm) without sounding as if you are just ascribing blame! However it needs to stick to uncontroversial facts - I think in the post above saying that the fire was caused by a steam engine would at the time have been conjecture and could turn out to be slanderous. It would be quite adequate just to say that there was a fire at the side of the track further down the line, and perhaps to add that no injuries have been reported.
It can also help with answering "why can't they" questions similar to those asked on this forum. For example the FGW crew could have said "As transferring passengers to another train generally takes at least an hour [or whatever] with a risk of injury to passengers, our company control has advised us that everyone should remain on board until we can get the train moving. Assistance is currently expected to arrive in... [whenever time]"
As I hinted at the top, and I'll repeat here, it isn't always easy to do this when there is insufficient information available. The whole industry needs to make it a priority to ensure that those in the front line have the information they need.
Sorry for the overuse of quoting, but I agree with all of the above.
Some people are more confident at relaying information than others. Some drivers don't announce the next stops on trains without CIS. Some even skip the obligatory safety announcement at the start of the journey. Some will go above and beyond their remit to convey information, some will give minimal information or not get drawn on anything - or even hide.
That's the same for any industry I am sure, and is probably more of an issue with drivers than TMs, who are presumably trained to speak to the great unwashed on a regular basis.
I am sure every TOC would prefer for staff to give information, even where exact details are unknown just to reassure people that a problem is in hand or being investigated. Even if the announcement might be seen as stating the bloody obvious, when a train isn't moving and people have already worked out something is up!
It's amazing how powerful a simple apology is and stating that you're on the case, even if at that point there's a lack of information forthcoming. Basic customer service, and something that a lot of people ARE already doing every single day. It's just the luck of the draw who is going to be working the service you're on, which shouldn't be the case.