There’s a good piece here by Chris Maclean on the death of regional variation, specifically in terms of beer selection in the licensed trade but also more generally.
It certainly seems to me that the overall experience of drinking in pubs was in a way more satisfying when the vast majority of cask beers – even those produced by the national brewers – very much had a regional distribution, so in a different part of the country you would be presented with an entirely different range of beers. Contrast this with the current situation where in so many pubs you are faced with a random “perm any ten from six hundred” selection. You can still find this in areas of the country with a strong presence of independent family brewers – such as Harveys in East Sussex and Palmers in West Dorset, but in most places it is very much a thing of the past, and something valuable has been lost in the process.