however PIK suffers from a perception of little attraction for inbound tourism in comparison with GLA.
I wouldn't have thought this would be the case. Inbound passengers, especially tourists, generally have little knowledge of the local area, and will not know which airport is most convenient for where they are heading. Therefore to them PIK is just as desirable as GLA, and often they won't even know that there is more than one airport serving the city they are heading to. Only repeat tourists would know the difference between the two and factor this in when making a booking.
It's only really outbound passengers who will make a choice based on the desirability of the airport.