Well, Im still under the impression that the option of a steam catapult is one that will be kept open and no decision is needed as of now. The Lizzie could easily be fitted with one at a later date. And our advanced Hawkeye EWA aircraft, which wont be operational for a few more years anyway, will also remain a viable option. The Hawkeye has already been show to be capable of a carrier launch using non steam arrestor wires anyway.
The thing to keep in mind is that many of these decisions simply dont "need to" be made right now. The ships are being built with flexibility in mind and flexible options, do'able flexible options, with be there in the future. Even the aircraft wont be ready at launch and the Lizzy will probably start off her service with Harriers. It all looks like very sound planning, and a very sound design, to me.
The important thing is to get them building and to save a British naval shipbuilding industry from disappearing. Many of the big decisions just dont need to be made right now.