Huh? A 10 year old cruise ship is just barely used. The Carnival Fantasy is about 22 years old and I believe is the oldest in the fleet. Heck, 9 of Carnivals ships (the 8 Fantasy class plus Destiny) are all older than Triumph...
Triumph is a machine and machines break down on occasion. Do you blow-up your car when it has a flat tire?
No tech baboon you don't blow up your car if it breaks down...but you also aren't reduced to flinging your own poop at others while you fight over the last onion sandwich if your car breaks down, are you? Get a U boat out there and slam a couple torpedoes into that wretched biohazard of a tub...
Commercial transport should never be compared to personal transport. Trying to do so, is strong indicator of a poor understanding of the differences. In commercial, the number one question is: Can I make a profit operating it. It doesn't matter if it's fuel inefficient, needs more dry dock time, needs more merchant marine crew (different than services). You can keep a ship operating for decades as long as you can handle the costs. The US Navy is still operating older ships that waste fuel & require huge support crews. Figure out how many radio operators are required on a modern ship, vs 15 years ago, and you have a good idea of how things have changed.
However, having said that, modernizing a ship costs. Also older passenger ships are direct drive, ie non-electric drive, replacing it (a huge engine) is a major headache on passenger ships. Almost all new passenger ships use electric drive, which are known to have issues with cascading power distribution failures.
On Military/Commercial, you try to eliminate common points of failure, ie dual port & starboard panels/wiring. Yes, they do have break downs, but as long as the operator doesn't try to operate equipment past it's expected life, you should be okay. It's when they don't replace, bad things can happen.
It will be interesting to watch this story...if the cause of this is related to a cascading power failure, maybe Carnival will ask the Italian shipyard for retrofit.