Because of the slightly odd reference to baggage sizes, this email smacks to me of someone in BA management saying "do something - anything - about baggage overloading on these flights". The HBOs will be further towards the back, and presumably sizes enforced (not that many people actually go over the limits), and made less attractive to certain regular flyers.

On the other hand they don't want to lose the ability to advertise an attractive HBO fare due to the various "cost comparison" websites out there which are perceived to play a big role in semi occasional travellers' planning.

That said, a number of routes appear to have lost HBO fares in recent weeks - the ones with less LCC competition where the comparison websites won't be so problematic.

BA will have to be careful about this one. From what I can make out some corporate travel websites automatically put people into HBO on BA, and therefore the choice to these relatively important travellers (to BA strategically) is indeed to go elsewhere if their FF status counts for little.