I'm receptive to the feature. But wouldn't it require locking the full table as it works? Seems like it would hurt availability of the biggest databases that would benefit most. Perhaps this is why it is thought somewhat impractical and therefore low-priority.
Depends on how the PG team decides to implement this feature. If they're OK with a virtual order (for "UI" purposes) while keeping the true order hidden then this would not require table locking (or it would be a very quick lock). If the order reflects the real / physical positioning then yes, it would probably require locking for a full table rebuild.
