SWBKCB - I'm not at liberty to say exactly how much (though if you look hard enough the figure can be found online) but the charter flights were costing the airport a significant amount of money per passenger.
The axing of charter flights coupled with the mothballing of 40% of the terminal is expected to cut the annual loss by as much as half, which is not to be sniffed at, as sad as the loss of flights may be.