First of all let me say I don't think this issue is specific to BA.

It's simple really. When an airline oversells it's aircraft, it's forced to pay downgrade or IDB compensation. When it oversells award capacity, there is no such compensation and the bottom line looks better. Accountants love that.

And if the liability of all those unused Avios/Miles/Points gets too much then they'll just devalue the whole lot spinning it as an enhancement.

I do like the BA program but the availability issue is a real problem. Even as a gold I am finding it impossible to spend my huge stash of Avios when and where I want to. Yes sure I can book F to PVG or NRT in winter but the marketing promises far, far more.

Frequent travellers do generally select airlines based on future reward possibilities but the fewer this possibilities are, the more transactional their choice of carrier will be.

It's also about time airlines are made to be honest about miles/points/Avios sold versus capacity released. After all, even the credit card or supermarket customers have effectively paid for their travel, except the restrictions on redemption are solely in the hands of the airlines.