That’s just how we originally sounded. Still should should.
Estuary is an improvement on the pretentious modern bollocks of RP.
The comment about heritage hit me in the gut. At school it’s common to be told you’re speaking wrong because you sound too “regional” as an insult aka not right off the banana boat.
Learning the wrong dialect actually shapes the palette of your mouth in childhood.
So really it’s a minor attempt at cultural genocide.
Tongue position is also a major factor in attractiveness.
The 50s deliberately tried to eradicate regional accents at school. People write papers about British accents. Like rhotic and non-rhotic.