[WillPS]

I suspect the single biggest factor is the decline in advertising revenue.

I believe the loss of a single sponsor was behind the closure of Club MTV.

For me personally, music channels have been locked in a vicious circle.

They clearly don’t generate enough revenue to justify carriage in HD and they fall further behind in picture quality.

HD has been standard for new music videos for a very long time and many older videos are now remastered / upscaled in 4K on YouTube.

With respect, I don't think the average music channel viewer really cares much about picture quality. At one point, pre-YouTube, they might be a place to go to see a specific music video, and for those people PQ might be relevant, but obviously those days are long over. What kept them alive is that it is (or was) convenient television. PQ really didn't/doesn't matter to that audience.

As an extreme case in point - I'm super invested in PQ; I've got a 4K OLED TV, a 4K Apple TV, 4K Netflix and Disney+ subs, must've spent £300-400 on 4K Blu Rays at this point plus a standalone player for them... yet when I'm in the mood to shove one of these channels on in the background it doesn't bother me in the slightest that their PQ is ropey. In fact I even quite enjoyed seeing the inferior copy of the Wham video a few times before Christmas.

I think the issue is more that people don't think to put them on any more - for most people I know the go-to for those situations is to shove Friends on Netflix these days (or something similar).