The way I see it is the move was 100% based on costs, yield never got off the ground in terms of BFS/LGW. They can now fly from STN at attract the majority of the same customers at a lower cost and similar fares.
It's still bad
PR giving up such a high frequency route to one of your biggest rivals (almost unheard of). There will be a lot of happy people at Luton today, they have taken a hammering on LGW over the last year or two.