A Road Sign in Kavala

Is it Konstantinoupolis or Istanbul? I've heard this argument going on an international news channel a few years ago. By then, I didn't quite get the need of discussion of such idea but as I saw this sign, I got an explanation from my father regarding all those arguments and learned something new related to our relations with our neighbor- Greece. In my opinion it shouldn't really matter to call Istanbul as this is the case for today's world and no harsh arguments shall be created over this which even end up with breaking one of the two side's hearths. Especially when we met this one guy in Greece as we were walking in the streets of Kavala and he asked with a broken Turkish if we were Turkish and when we said yes, he replied with a Turkish phrase saying we are all brothers and sisters. I think this shall be the end point of all arguments. Because, when you think- aren't we all brothers and sisters, the people who share this planet???