It was only a matter of time before something like this happened to a large cruise ship - just be thankful it happened close to shore and not mid ocean.
I wouldn't be horrifically surprised to see this caused by too many people putting far too much faith in Bridge electronics - as is scarily common today, almost approaching 'the norm'.
The Carnival empire employ a bridge management system called BTCC which is similar to the way aircraft work in that it has a Pilot/Co-Pilot concept, plus (going into Port) the Old Man, Navigator, Staff Captain and numerous ratings on the bridge, all supposed to be feeding information to each other and cross checking each other. That falls down of course, if you're all staring into the same ECDIS screen which is chucking out an erroneous position and nobody is looking out of the window.
Questions will also be asked about why she rolled over - being a new ship, she will have been designed to the latest (and very strict) damage stability standards - hull subdivision and the ability to cross flood is supposed to minimise the possibility of capsize.
Saying that, I know a Naval Architect who designs Super Yachts for a living but also conducts salvage operations, and his opinion is that if 'Titanic' had been designed with the same subdivision rules as modern ships then she wouldn't have slowly sunk by the head, but would have capsized and sank far quicker than she did.