If cryptocurrency is supposed to bring the benefits of decentralization to the masses and usher in an era where the "little guy" is more free, it needs to solve that equation somehow.
As there will be no way back from a bad social score, this is coming.
The key problem to solve is how to create an exchange that the authorities can't shut down.
When visiting Sweden recently, I was surprised to find a number of bars, coffee shops and the like only accepting digital payments - no cash. While this makes lots of sense from the vendor's perspective - handling cash is expensive and inconvenient - a customer may feel different about it.
These vendors presumably decided that the benefits of not having to handle cash outweighed the risk of alienating a small percentage of their customers (As 'everybody' in Sweden carries debit cards and cell phones with e-payment solutions, few people rely on cash exclusively).
Now imagine what happens if the authorities also held the power to say that you WOULD not accept cash.
That would make anyone assisting someone with a low social score buy items normally not available to them an accessory to subversion of the state (or something similarly eerie-sounding).
Not good. Unless you are The State.
I agree with all your other points, but e.g. in China people may soon wish they still had a decentralized payment system. Especially if you have a low social credit score, and the government starts to decide in detail what you can and cannot buy.