This is a bad move. While I don't disagree with the issue they are trying to solve, centralizing the directory control is literally against the goal of the protocol itself. They should have created a proper replacement system instead.
Did you read the same post that I did? Where does it say they're centralizing the directory control? This post reads to me like it's about an individual server instance, not the whole network.
It's not centralized by implementation, but that's what it does in practice. matrix.org is by far the biggest instance and now all the other public rooms will be hidden on there unless someone manually approves it. If more instances move to the same offered default preference now, discoverability is dead.
I don't know if I would classify it as a bad move, but it's definitely disappointing. Something like this should have only been deployed as a last resort. Perhaps it was.