In this business where aircraft are bought "off-plan" often before they are even designed, it's more about the bean counters, than whether they are the ideal aircraft for their routes.
Really? When I was an accountant, I witnessed aircraft selections on which my firm advised whose primary purpose was to find the ideal aircraft: I think you are confusing the management who achieve a poor bargain, with their accountants...
The aircraft are ideal for high-yield routes at a slot-constrained airport, where additional frequencies, though desired, are simply impossible. Sending 4 of them to NY each day out of the 7/8 flights (not to mention Newark) would not only be sensible, but enitrely profitable. You only have to look at the routes which have two 747 departures within an hour of each other to see where consolidation might be possible, to free up BA's Heathrow slots for other routes.