The lack/loss of identity and the culture coming out of the northern towns/cities is definitely something that has changed (in my view). Everything is so centralised around London, all media/art has to be diverse which means the identity of the places that are being represented aren't accurate depictions but are instead more homogenous, and usually played by people from London or at least people that now live in London. Financially it is harder to pursue a career in music/acting so most of them come from similar (wealthy) backgrounds.
Student numbers increasing so heavily over the last 30 years has meant that people are far less likely to stay in one area. Even big cities with big identities like Liverpool, Manchester, Newcastle etc are very cosmopolitan these days because they have had so much immigration from students around the country. Bands are as likely to meet at university than their home towns which means there is less chance of them having a shared background etc. None of those things are bad, it does reflect the world we live in better than how it was 30 years ago but it does make it easier for southerners to dismiss the North if there is nothing unique about those places.
Financially London is just leagues ahead of the rest of the UK. There is so much investment there that it is frankly ridiculous. The wealth radiates from London so the majority of the South still within touching distance feels connected to it. As you get further away, in all directions it is far less. The rest of the South must look at London the same way the North does but they also look at the North the same way Londoners do because that's what they are shown across the media.