It isn't just the news channels. The national rail website today decided to make their website grey as a mark of respect.....until they had to change it back to colour because no-one could read it. That's ridiculously OTT. Who on earth decided that would be appropriate, or a good idea?
I don't think having significantly more news coverage than normal is a problem; he's a major figure in the UK and although his death wasn't unexpected at his age, it still deserved some of the attention it received. However, having reporters stopping passers by in random American towns to ask their opinion is completely over the top. It's mostly caused by the incessant need to feel like you have to provide rolling 24hr news coverage to compete with Sky. Note to the BBC - if your presenter is having to ask people if they think the Queen will miss her Husband of seven decades, then there is nothing left to say and the programming should return to normal, perhaps with extended news bulletins if necessary.