First of all decentralization is not a property solely confined to cryptocurrencies. The traditional banking system is decentralized, there are thousands of banks that are all separate entities. There is no single central bank, even central banks are not unique, every country has one. Additionally the traditional banking system and cash have a huge advantage, no global consensus is required, Iran still has a banking system much to the dismay of the American government.
> *Control by a majority, not a minority. (democratic)
It's a majority of hash power in the case of PoW and a majority of capital in the case of PoS, since hash power costs capital in both cases it's a majority of capital that has control, oh and the systems devs of course a small group that essentially decides the future of the system.
> * Open ecosystem that visible and able to be analysed by anyone (transparent)
That is not necessarily a good thing, the fact that all the transactions are public means that they can be analyzed to identify people, this is bad not for criminals that will use sophisticated anonymizing techniques. But casual users that don't know any better and maybe identified doing either illegal (buying drugs), compromising (paying for sex) or simply being associated with other known users. In the traditional banking paradigm these problems are usually circumvented by using cash, or relying on the institutions privacy guarantees when no law enforcement is involved.
> *Immutable
All these schemes while claiming to be immutable are really not, firstly the last block is always subject to being overridden by a longer chain with more blocks, thus everyone waits for multiple blocks(confirmations) before accepting a transaction as committed, secondly even if the development team / or the majority of the miners does not like a specific transaction they can always revert it, by controlling / or being the majority as was the case with the events that lead to the existence of ethereum classic. So these schemes are not really immutable, they are only immutable when a single users tokens are stolen.
As for me, I don't believe that cryptocurrencies are completely useless. I just don't see why everyone is so excited.