Language does change all the time, so we do have to accept that various words change pronunciation. When I was a child many of my grandparents' generation still spoke of "a chimist's shop" not "a chemist's shop" and now even British people seem to prefer " a pharmacy".
However, as language is primarily a means of communication, I still feel we need a standard form of both the written and the spoken language.
I'm sure it was not only in Scotland that we who were children in the 1950s and 1960s could speak both a standard form of English and "broad Scots". A standard form for use at school, on formal occasions and when speaking to those from other parts of the country, broad Scots i.e. Doric Scots when speaking to those who used it, and broad Glesga when we went into Glasgow - the seven miles between Glasgow and Barrhead resulted in two different dialects, Glesga and Borrheid.