There is such a thing as standard English, Received Pronunciation if you like. It’s no good pretending there isn’t. If you have half an ear, you know it when you hear it. It isn’t snobbish to prefer it to regional accents. There’s a lot of inverted snobbery on this thread.
The attitude to regional accents changed in the sixties, when there was a minor revolution in social attitudes in general. It coincided with the Beatles, though whether they were the cause of it or the result is debatable. Before that, in the 1950s, as I remember it people tried to speak ‘properly’, at least in the middle classes. I remember a girl at school being devastated when somebody implied she had a northern accent. By the sixties, some people put on a non-standard accent if they didn’t already have one.