Here are the most important qualities a true Cryptocurrency must have:
A true Cryptocurrency must be decentralized, public, trustless, permissionless, immutable, transparent, uncensorable.
These should also be very important rules of Cryptocurrency which developers must try to stick with. Exchanges ordinarily should not list Cryptocurrencies that Break the rules.
Decentralization on the other angle, is more like you being given that control back and you are free to do what you want to do with your activities as long as you are not going against the laws of your jurisdiction, and that is something I will always choose anytime any day over centralization. One of the reasons we are here in the first place anyway.