Bastardeux,
I think you have valid points and some will always fall on either side of the fence as regards the carrier debate.
Interesting to me, though, given your figures of 15 billion for (both?) QEC carriers and 6 F35B is the price tag for Typhoon - which you would buy instead.
The NAO quotes 20 billion down and 17 billion more to come, for Typhoon, and IRRC we can field 16 (FE@R might have gone up - admittedly, but with a total buy of 160 I can't see it getting much above 30 or so) and they aren't going to be fully up to spec until 2018.
That seems like a hideous cost for what we actually get given that the F-3 was more than capable of providing homeland security and Falklands QRA.
But anyway, it's a knock F-35B and carriers in the main thread, not a 'golly how the Typhoon's crippled us' thread - so I do apologise, but I think we need to compare like with like.