It's not necessary and it's not the main purpose of Bitcoin. There is a huge difference between fiat currency and Bitcoin. The purpose of creating Bitcoin is not to become an official currency from what I understand. Maybe you can find out for yourself what Satoshi Nakamoto's motives and goals were in creating Bitcoin.

If a country wants to make Bitcoin an official currency it's up to them. And vice versa.
The Bitcoin operating system is not centralized. That's what needs to be remembered.