I assume that the business model for many airports was attract the airlines with reduced fees and earn revenue from what the passengers spend in the various shops cafes etc. However I do not think the amount spent by each passenger has met expectations. I myself as a frequent traveller treat the terminal as I would a bus station. I just pass through and do not use any of the facilities so do not contribute to the airport income.
Options for the airport, try and get more money from airlines. ( Ha Ha ) or find others means. Net result drop off fees. Either way I as a passenger would pick up the cost.
Difference between BOH and the likes of LTN, STN etc is they have viable public transport options so there is a choice. Also it would be nice if the first sign you saw approaching BOH would be Welcome to Bournemouth Airport, not PAY £2.50 or else.