increasing capacity although reducing frequency
Since when has frequency been important on any ultra long-haul route? Frequency is only important to business and connecting passengers, but the first thing you do when you get off the plane after an 11 hour flight is go straight to your hotel to let your body clock recover. If you have a meeting in LA, you'll probably arrive 1-2 days in advance just so you're well rested; by which time whether you arrived in the afternoon or evening is irrelevant. And with regard to connecting passengers, I doubt LAX is a hub for connections from Europe - they all transit on the East Coast. For instance my mum's been to America twice this year, once to Las Vegas (via Charlotte) and once to San Diego (via Newark).
So, bearing that in mind. It makes sense to replace 3 747s with 2 A380s. You keep the same number of seats, the passengers don't mind the loss in frequency but you save a hell of a lot of fuel. And as a cheeky bonus you've also freed up a slot at LHR to be used for another route