In WWI it was clear that defense is better than offence when the German and British navies met. The British cruisers sank and the German ones did not as they had better armor. What has changed since then other than the fact we abhor casualties even more now than then? Can anyone show why defense shouldn’t be the priority.
Actually, it was poor tactical doctrine. The British got sloppy with their ammunition storage and handling.
Because it isn't WWI anymore. Offensive weapon lethality has overtaken the ability of defensive measures to cope.
Because WW2 showed now matter how armored the ship, planes will sink it eventually. By the end of the war radio guided bombs were blasting the crud out of things. Even Kamikaze showed the potential of guided missiles. Basically they realized you CAN’T put enough armor on. If you can’t shoot it down before it hits, you are screwed. So defense is offense now. Again.