The procurement itself was the issue in the carriers case; the general specification and the intent was for ships convertible between what we have now & conventional catapult launch/arrested landing. The story I was passed was that the actual procurement wasn't worded sufficiently tightly & the supplier decided to work with the letter rather than basically ask if the procurer was sure this is what they wanted, so while the carriers are technically convertible it'd cost the same as building a new carrier. That lack of desire to deliver good value seems very common in recent years. I wasn't really referring to anything particularily to do with engineering itself ( although the horror stories I get from people in engineering right now would make me pretty nervous if I wasn't fairly sure production lines had always been that way... ).
That is very different from the story which I heard and read about in journals such as Flight and Aviation Week.
The carriers were designed from the outset to be compatible with the F-35B, the Short Take Off and Vertical Landing version of Lockheed's Joint Strike Fighter. This version was considerably more expensive that the more conventional F-35A which does not have the extra lift fan behind the pilot, the downward swivelling engine exhaust nozzles and the bleed air system for low speed attitude control. However operationally it uses the experience which the Navy built up over many years of Harrier operations.
A Secretary of Defence — whose name I can't remember — decided that he would would change the order for F-35Bs to F-35As and save a shed load of money. This decision came as a great surprise to the ship builders who would have had to have redesign the flight deck completely and install sufficiently large steam generators to power the catapults in a ship which had largely been designed. The latter was somewhat difficult as the ships were to be powered by gas turbines with no capacity to generate steam in the quantities required. It was also a surprise to Lockheed as its production planning would have to have been completely re-jigged and an additional effect was that the unit price of the F-35B would have increased because of the smaller volumes. The US Marine Corps, one of the major operators of the 'B' variant was not amused.
Eventually sense prevailed and the ships were built as intended. In any event I cannot imagine how a 'ski jump' flight deck profile can in any way be compatible with the design requirements of steam catapults. Unless, of course, the ship is very much larger than those built.