What is the reason why NXT decided to create a child chain? Isn't NXT enough already or is there a technical reason why? Could this be a sort of "reboot" for marketing purposes.
In a glance this looks like a move driven by marketing reasons since NXT really went anywhere in that regard.
Running a blockchain is costly and many entities don't have the expertise.
They would like to use a blockchain to solve various problems and not worry about security, blockchain maintenance, volatile coin rates. In Nxt 2.0 they will get specialized blockchains with custom features, for instance they can peg their custom blockchain token to one USD or cowry shell, or their custom blockchain will be feature tailored to their specialized usage. It's a blockchain as a service thing. They will pay block fees to the global network of ARDOR token holders when they must make a hashes record of their custom child chain operations into the main chain. It's a 'focus on your job without all the worries that come with running a blockchain' customer-oriented solution. Transactional throughput will grow manyfold.