Can you explain exactly what you mean by deep manual re-orgs? There is no such thing in NXT. As far as I know the re-orgs are fully automatic, based on the rolling checkpoints 720 blocks deep maintained by each node's software as a distributed consensus.
Pretend you are in China and the "great firewall" cuts Chinese "forgers" from the rest of the network for 3 days. What happens when they reconnect with the rest of the world? Obviously, somebody has to force the re-org manually.