Now we will see if NXT is decentralized or not 
rollback = centralized
rollback = centralized
Not really. It takes all the decentralised nodes to agree and form a consensus.
That's like calling Bitcoin centralised every time they upgrade the software.
haha what?
When bitcoin upgrades the software there is no rollback
Do you not see the difference?
How is x amount of individuals separate from each other centralised?
When Bitcoin upgrades the software or has a hard fork the miners and the nodes need to agree on using and mining on a new chain(in the case of a hard fork).
It's a decentalised consensus either way.
That's the whole point of decentalisation. That it takes the majority to make changes.
I'm not saying that I necessarily support the forgers choosing to roll back or not though. But it clearly isn't a centralised decision.