If judges have the last word on who owns how many bitcoins why are you wasting all that electricity for? I thought it was to avoid relying on an authority...
My understanding is that decentralization helps avoid things like runaway inflation or banks deciding at will how much money they want to siphon off each transaction. If you are stealing someone else’s money, a court is not going to dismiss charges just because the transaction is not reversible according to the protocol of whatever cryptocurrency you used.
Decentralisation doesn't help with inflation, it only makes everything more expensive due to the extravagant cost of the consensus mechanism. Banks are already decentralised (should be obvious since there are many banks, not just one) and competition among banks is what prevents them from charging high fees.