Minogue you are wrong about Cardiff, it has an immediate catchment area of 1.5 million people, is home to over 350 US owned companies and countless European owned. The greater catchment area covers the whole of South and West Wales right down to Pembrokeshire since there is no other airport of credibility there (yet!). As has been stated elsewhere it is a vibrant place and economy and the WTB and WDA are doing and spending a great deal to make the place grow. TBI too are doing a great job. It is true the approach (road/rail) to CWL is awful but plans are in place to improve this.
Of course CWL will never equal the catchment area of LTN so it would be folly to assume the airline would even consider moving its base there.
I knew Stelios before easyjet started and when it was a twinkle in his eye and he was running a fleet of tankers, he was told by the experts then that Luton would never work and 'it was the wrong place', despite this he was determined to start there and look what has happened. He would have no fear in taking the risk at Cardiff and rightly so.
Finally I am not Welsh but have studied the Cardiff market over the last three years in detail both charter and scheduled, I assure you it is among the fastest growing in the UK..... easyjet + Cardiff = recipe for success. Let's hope they do it.