Firstly, I don't value Bitcoin in fiat, but in its purchasing power. I may need to relate that to a fiat currency, but that is really just to acquire it through an exchange. Even when you do value it in fiat, then it is international, so it is not just one fiat currency that is being used. Interestingly, its purchasing ability may vary from country to country - hence the opportunities for arbitrage via local exchanges.
Bitcoin should be treated as a currency, the fact that arbitrage opportunities or any profit making opportunities should be considered independently of its core function.
What I am suggesting is that people who are not trying to evade taxes, or indulge in activities that some may consider undesirable, may not have privacy as the primary attribute of Bitcoin. If you use an exchange with KYC, then you are a long way closer to my suggestion. One might even say that you have already embraced it.
Would it really make you less secure if the database was hacked? Would it really leave you vulnerable to a £50 wrench attack ( price adjusted for inflation )? At least it make make any perpetrators easier to discover.
You underestimate the importance of privacy to most. The reason why privacy appears to be a smaller issue than it really is would be because of the lack of education and knowledge. Privacy is
important and a fundamental human right. If it doesn't seem to be important to you, then I believe fiat would be far easier for you to use.
There is also an assumption that people who want privacy are necessarily people who transact in illicit funds or are involved in them. This is false.
Remember that Bitcoin is pseudonymous , so most of the info is easy to discover anyway. If you really want to indulge in illegal activities, use the currencies of the elite. These are high value gold coins such as the English Britannia and the Sovereign ( the coin, not the woke prince). They are exempt from VAT, gains tax and inheritance tax in the UK, so you can work out how keen the government really is to stop fraud and money laundering.
I just feel that registering your wallet with the government doesn't really give anything away, and may lead to simplification of the use of Bitcoin.
Pseudonymous != Zero Privacy. If you think someone can easily track your transactions, then you do not value privacy and you should absolutely declare all of your transactions and every single one of your activity to the government. Bitcoin is designed to be pseudonymous, and it cannot be done without the users intentionally taking steps to ensure this. Issues should not revolve about whataboutism but should focus on what we should achieve with our privacy.
Of course you may elect to have an undeclared second wallet, and that would be your choice
Don't you think this defeats the purpose of your suggestion?