If you will make Bitcoin reliant on a country, you would only weaken it, because the country could be sanctioned or invaded.
It wouldn't rely on that country more than it relies on El Salvador nowadays.
I can tell that many people on this forum are unhappy about the treatment that bitcoin has in term of taxes and restriction. Those that have a significant amount may be interested in living in a crypto friendly jurisdiction and that is simply not possible in many countries. These people could potentially benefit from creating their own jurisdiction, based on the principles of self-sovereignty, crypto friendliness,...
I'm surprised you would say this, as I understand you have a more social democratic view of economics and politics than I do, and you are positing a sort of tax haven where people who have a lot of Bitcoin could escape.
On the other hand, this would not necessarily be the case either. I do understand that if the country were formed, it would initially have low taxes, but there is no guarantee that in time a socialist would come to power who would increase public spending, put more regulations and more taxes. That the only legal tender was Bitcoin does not prevent a politician from putting high taxes. What happens is that since with Bitcoin it is more difficult to know what you have/earn, taxes would have to be indirect taxes.
Apart from the fact that Bitcoin would be the only legal tender in that country, in order to trade with the rest of the world, that country would again have to have money reserves in other internationally recognized currencies - unless it is 100% self-sufficient, which is impossible.
You don't have to. Nowadays you exchange currencies at the click of a button. Not to mention that it won't be long before we have a digital dollar, digital euro, etc.
In addition, I agree that any centralization of such proportions is bad for Bitcoin because it creates a central entity that can be held accountable for what Bitcoin represents. Satoshi, in my humble opinion, decided to remove himself as a central figure for this very reason, and that is why Bitcoin is such a success.
I do not agree with that. Bitconia would not centralize Bitcoin in the same way that El Salvador has not. It would still be just as decentralized.