For example Azeris, Turkmens, Tajiks transitioning from the Arabic script, and Buryats from the Mongol script.
And why wasn’t there a cyrillisation of Georgian and Armenian?
To me the script changes seemed unnecessary, but I’m curious what you think
Turkic languages that use/used the Arabic script extended it with additional letters and diacritics.
That’s true and that’s the reason why Turkic people had low literacy rate. Arabic has 3 vowels and modern Turkish has 8. Back in late days it has too much effort to learn but now language itself literally got rid of its own unique sounds to fit in to Latin alphabet.