I have never really seen that many cheap flight only seats available during the week since it went on sale.
What BA and others tend to do is only offer full fare flight only prices and sell off the cheap seats in flight and hotel packages. If you were to look at a package to NY on expedia for example, for 4 nights in NY departing 10th August, for a mid star hotel and direct flights from NCL it is around £1100 per person. Flight only for the same dates is £1260pp so MORE than a package!
So it could be selling well, or, all the cheap fare buckets have been bought up by Expedia and other travel companies for packages.