Although it is my understanding that the names Istanbul and Constantinople are both of Greek origin, its hard to imagine the latter having not been of immense cultural and historical significance to the native Greeks of Turkey, especially to those who knew the city as home.
With this in mind, it moreover seems oddly suspicious that the decision to officially and permenantly retire the name Constantinople convienently coincided with a time when nearly all of Turkey’s remaining Greek population just so happened to live in the city. (see Lausanne Treaty). Perhaps I’m being overly cynical, but surely this cannot be purely coincidence, no?
All that said, how did the Greek populace actually feel about the decision? Were they upset or did they not even really care?
it's not actually a coincidence. In 1918 the city had two names in use. While names based on "Constantine" were used in official documents and among minorities, the name based on "İstanbul" was common among Turkish people. During the Occupation of İstanbul, the Greek minorities in İstanbul, who were Ottoman citizens, called the occupation armies in connection with the name of the Greek King Constantine I at that time, "Here is Constantine (İstanbul), here is Constantine!" greeted with cheers. This cheer spread and turned into a slogan. Thus, the name "Constantine" took on a very negative meaning among the Turks. One of the first things done with the retaking of İstanbul was the official replacement of the negative name "Constantine" with the name "İstanbul".
References; Afyoncu, F. (2009). İstanbul During the Occupation Period According to Ottoman Archive Documents (16 March 1920-31 December 1922). Unpublished Master Thesis. İstanbul: Marmara University, Türkiyat research institute, Ataturk's Principles and Revolution Department.
In addition the boundaries of the city changed after the proclamation of the republic. Conquered Constantinople is the Fatih district of İstanbul. (Fatih means Conqueror and the name of Mehmed II among the people is Fatih Sultan Mehmed) After the proclamation of the republic, the names of more than 20 cities including Konstantiniyye were changed.
Btw according to Haluk Tarcan's thesis, 'İstanbul' comes from its pre-Turkish (astan-bolıq) origin. The word 'asqan-astan' meant 'land of god' in pre-Turkish, and 'bolıq' meant 'city'. These two words, "Astan-bolıq" give us the meaning of "heavenly city". "Astana" means capital in Kazakh and has the same root.
but this is a very questionable subject for me
This is the first time i've done research on this subject, i never thought until i saw your question. Thank you for making me learn and i think i'll go and listen to the song "The four lads-İstanbul" now (i recommend)