all that investment and capability still needs the optimum protection....as the Falklands showed - the loss of a carrier would not only have been militarily difficult to cope with (and we had 3 in those days!) , but politically would probably ended the war for us.
We didn't have three carriers during the Falklands War, we had two: Invincible and Hermes. Illustrious and Ark Royal did not enter service until after the Falklands War.