Why not just use NXT itself? What utility will this feature provide?
Different properties than NXTs.
Different use-cases than NXTs.
Diversification.
Ah yes, and
brings a bit of sidechain flair to Nxt. 
glad Im not the only one who saw that. and with the way BTC seems to be foundering on the subject, my guess is MS will come out long before sidechains do