There's a point at which rewarding these flyers over and above those who pay much more for less convoluted fares becomes counterproductive though.

As an aside, I'm not sure there's as much choice as you think from the UK to HNL (and this point is of borderline relevance anyway, the implication is these flyers only go to HNL *because* of the attractiveness of the route as a BAEC earning opportunity rather than because they wanted to go and therefore chose BA/AA as the best option).