Carriers can also be bombed, or even hit from over the horizon missles.
Fairly cheap those AShM when compared to a carrier and a runway that is listing significantly to one side is far harder to get back into operation than one (of possibly a number) that have been cratered.
Also there is the small matter of all those aircraft squeezed into a small space rather than dispersed over a large distance on an airfield when that fast, pointy and explosive thingy hits.
Yes the allied air operations showed in Iraq that, given a sufficiant amount of assets, airfields can be knocked out. But as a certain South American country showed not so very long ago, given a small amount of AShM some serious damage can be caused to the opposition, especially to large vessels carrying aircraft.