WEBF - One could probably state that the genesis for the QE ships was the very rapid evolution in US combat aircraft plans post-Cold War and post-Desert Storm, including the demise of A-12, the invention of all-service STOVL/CTOL/CV fighter concepts by DARPA, Lockheed, Macs and Boeing, and the early-1993 binning of A-X and MRF.
The subsequent emergence of JAST/JSF magically "solved" the Marine/RN problem, which was not just the difficulty of defining a supersonic STOVL Harrier replacement, but the fact that funding such a thing was hard to justify in the Cold War and almost unthinkable after it. I don't think anyone would have been very excited about building new carriers to operate a Harrier III.
Of course, it was purely an accounting gimmick and not a real solution. Developing a stealthy STOVL fighter (including a monster engine you didn't otherwise need) was always going to cost a ****ton of money, but if you rolled that in with the CVs and CTOLs and projected you'd build 4000+ units, the program acquisition unit cost - (R&D + Production)/Units - didn't look ludicrous. Basically, most of the STOVL cost ended up on the USAF and CV Navy tab, which I suppose that (if you are RN or USMC) is as close to an economic miracle as you can get.