The point is, not all information has the same importance, nor is a scrolling dot matrix display using exactly the same words as a simultaneous audio announcement always the best way to deliver it.
Next stop, destination, real-time information - by all means.
"Hold the handrail if it's raining and there isn't anyone who looks like a terrorist around" - should at most be a poster, if it is necessary at all.
To take my point to the extreme, stations nowadays generally have lots of advertising posters everywhere, but (thankfully) nobody seems to think it necessary to have an audio advertisement for every poster.
The aim shouldn't necessarily be to supply everyone the same information in exactly the same way, at the same time, but to ensure that everyone has access to the information they need, when they need it.
One tangentially related aspect that annoys me in that respect is the complete reluctance of UK station operators (and airport operators too) to place any information displays at eye level. Placing almost all departure boards high up near the ceiling, no matter how big they are, makes them inherently inaccessible to people with visual impairments, where they could otherwise walk up close enough to read them in many cases. In other words, poor design makes stations less accesible than they could and should be, and excessive announcements are not the solution to that.