Our political lords and masters (sorry elected representatives) are spineless cowards. The major advantage of a carrier is not the comparativedly limited teeth, but that you can send it to chug about in international waters while you are dithering or negotiating with nearby nations for use of their airfields. I think that the doctrine wallahs call this "poise"
Like the completely unusable and costly instant sunshine alluded to earlier it is something that buys a seat in the stalls. This is why new Labour has conveniently forgotten about it's previous stance on unilateral disarmamment...
Configured with a decent rotary wing complement also rather useful for NEOs when diplomacy fails and you cannot get permission to use a nearby airfield...
Even the Italians are building a new carrier, due in service in 2007.