Whilst they are impressive ships in a technical sense, the consequences of one of these behemoths foundering doesn't even bear thinking about. Circa 6000 passengers and just over 2000 crew with only a handful of professional seamen amongst them.
Even if they did manage to abandon ship with no casualties, there isn't a maritime nation anywhere in the world with the Search and Rescue capabilities to be able to recover and care for the survivors.
Naturally it will only take a major disaster for the regulatory authorities and bean counters to realise that.