Seats for sale cap is an excellent mechanism for controlling growth at BHD. IF removed BHD could expand to 4 million pa without going over the cap on flights. This would upset the aviation balance in NI. Noise pollution is a massive issue at BHD and must be controlled. Most professionals who are in the know would realise this so I wouldn't expect it to be removed - however never say never.
If I remember correctly the analogy in defence of the cap removal from management at the city airport went something like 'it's like having a 300 bedroom hotel and only able to fill 250 rooms'. Well why did you build a 300 bedroom hotel when you knew you could only hire out 250 rooms?