There is nothing "magically good" about block-chain-based currencies; they are not a panacea for a "better world", whatever that is.

Too much still depends on the intentions of those having, or controlling, very large stakes; some will do whatever they can to create or mimic a system that serves them best, and when their stake is large enough, it is hard to stop them. I suspect that colluding large stake owners can always concentrate wealth even in a decentralised system and use the associated power to manipulate.

As so often, I hope I'm wrong.