my answer is very similar to many others:
they don't need it yet.
I don't think they would want to waste their money in the far future
see link below:
Space: The Aircraft Carrier Killer Satellite
THe point is If china builds it no doubt India wlll follow suit, since its able launch satalight and has done so in the past, which put Pakistan in a very dis-adavantage.
Besides China its on its way to develope an Carrier killer Missiles.
http://news.yahoo.com/s/ap/20101228/ap_on_re_as/as_china_carrier_killer
I think the Carriers are like the Battleship of the past - small fast moving warships and submarines with small drones and Cruise missiles will play a MAJOR role in Maritime Warfare in 21 century instead of Big bulky ships like Carriers who are a greater targets for Missiles.
Second, it would be a matter of time when Jet fighters will become so advance in speed, flight range and time that the need of carrier will be come completely redundent.
Israel started this with f-16i and think Russia has something as well.
Just think what Carrier is for, to launch fighters at sea. If such jetfighter in the future can get to hot spot in 15 min half way across the world, still have enough fuel to stay in battle for 8 hours and then after that has enough fuel to go back home safetly - who needs an aircraft carrier ?
Pakistan should not go for the carrier at all and concentrate on Subs and drone carriers. A HEllicopter pad carrier or a ship thats no bigger than 180 meter like Príncipe de Asturias from spain, if they realy really really need one badly, but not a big massive one like Enterprise or Nimitz Class.
furthermore, if it does decide to have then pakistan needs to have a good portion of these small CArriers to be effective instead having one small carrier so money is a Major issue which Pakistan can not thrown away lavishly.
In conclusion, Pakistan Navy is much better off in having Subsmarines and Frigates or a ship that able to carry multiple of drones for sea, submerdged and air and launch them in large amount .
Storm Force
You forget THe US Russia and China operates serveral large carriers
but France and UK operates meduim sized carriers in small amounts
SPain India and Brazil only have 2-3 which is not much.