Why is this good?
As with cash, however, it would be foolish to imagine a future where every person holds their entire life-savings directly in a wallet they personally control. There will always be a need for safekeeping of large amounts and there will always be a need for large, liquid marketplaces to exchange digital cash for other assets. Multi-sig wallets and decentralized exchanges may, one day, make these safekeeping and exchange services less dependent on centralized entities, but full decentralization is probably an unattainable utopia (and maybe even an undesirable one).
Peter Van Valkenburgh - coincenter