You don't need to me to say again that BAA's appalling, high cost and ultimately uncompetitive management of Stansted
It's really easy to have a go at BAA but they built Stansted to be a new London hub airport for the 21st century then had to make money out of it via Ryanair and easyJet. That's a divergence straight off the bat, STN is a really nice airport with a very loco demographic and feel to it. "Uncompetitive" as you say is the necessary requirement BAA had to cover their costs once cross subsidy from LHR was stopped. By all means lets see how MAG do with STN on it's own two feet dropping prices to lure back EZY. It won't be easy to make money though, Ryanair's biggest base is at STN and BAA weren't rolling in gold as a result. High load factors and millions of passengers can still mean the airport operator loses money. Stansted is faced with being a base for the cheap and cheerful with the overheads of a major international gateway.