Must disagree there Jim. If you work where I think you work, you'll be aware that "useful" doesn't cut it when it comes to requirements (as we're finding out).
It is a complete and utter fallacy that the size of QEC is solely driving its cost and that a "smaller" carrier would have been significantly cheaper or more cost-effective. However, the perception that the size of the ship would make it vastly more expensive than a smaller ship is something that has continuously dogged the project from inception. This was compounded by the failure to uplift the LTC lines for the project between 1998 and 2001, when it became clear that the 40000te "concept" produced for the initial costings would not be able to generate the sortie requirement (since walked back on, but still well in excess of that which a CVS could deliver), which required a somewhat larger ship of 60000 te. Note that the funding difference at that point was ~£500m (£2.9M original budget, vs £3.4M price submitted in 2002). Subsequent cost growth is not related to the size of the vessel, but to the endless b8ggering about with the programme and associated risk - delaying the programme has incurred by far the majority of cost escalation.
A "smaller" carrier (non-CTOL) would also by definition have been locked into the Dave-B programme, which if it went t1ts would render the ship irrelevant.
Your points regarding the size of RN CAG are unfortunately all coloured by the fact that those carriers were war-designed and built for piston-engined a/c and subject to the huge growth in a/c size and weight between 1945 and 1970 - a factor which no longer applies. The "zenith" you refer to was arguably in the mid 60s, when Eagle, Vic, Centaur and Hermes (none of which were "Light Fleet") were all operating with Ark in refit and CVA01 projected. All the original light fleets had gone by then, with Bulwark & Albion as Commando carriers.
As for the CVS CAG - as I understand it, with 16 f/w aboard, there was only room for the baggers and maybe a Lynx or HU5 for HDS etc - the Merlins were elsewhere. If you wanted pingers, then FW dropped to a dozen at best.