Having a centralized currency would be not safer than decentralized ones because when the one who controls the currency will be attack then all of the system will be affected while in decentralized ones, even if one is hack, there is still a bunch who controls the system so it cannot be easily destroyed. As for Government restriction, if they decide to make the centralized currency then they can just easily shut it down since they are the own who controls it as oppose to decentralize ones wherein no one has full control of the currency.

Since centralized cryptocurrency is controlled, they are easier to ban as well. If some of the countries would like to oppose the current decentralized cryptocurrencies then I think they would create their own cryptocurrency to combat it and only allow its citizens to use it. Centralized cryptocurrency is just analogous to fiat currency anyway since government has control of it.