when you only have multi-billion dollar carriers you start to worry about putting them in harms way - eventually they become so valuable they are so far back they can't do what they were designed for
The original purpose (way back in the late 50's) of the modern US carrier group was to be able to launch N-bomb equipped strikes against the evil empire - since then they have morphed into general force enhancement, showing the flag etc
The danger is of course that when they are involved in a hot war we discover that anyone can sink one - then we're in the position the USN & RN were in in 1941-42 when aircraft made battleships redundant - up s*** creek