the way of hows naval fought has change so much since those time , modern naval ship fought each other in much longer distance than what Battleship used to fought (ex.cruise missile out range 16" gun )
modern ship prefer to defense it self by using active counter measure rather than passive armor , thats why old warship are sooo heavy dont forget too include their main armament
thats one of the reason today ship survivability is really suck IMO , its a give and take ¯\_(ツ)_/¯