There's one case, though, in which I justify the use of centralized exchanges: If you're sending (or receiving) a lot of money via a bank account or another financial institution and there is no legal framework for cryptocurrencies in your country.

This is some trouble, because not only do you have to somehow justify the transaction to the bank, but you also have to be aware of some special-arbitrary treatment from the tax office. Using a centralized exchange is probably going to pull you through the former, but I'm not so sure about the latter.