Yes, the airport needs to make a profit to be viable. I simply feel that this is a pernicious method of achieving it. If this was introduced at my local airport, I would get out at the roundabout (at the airport entrance) & walk the 200 yards to the terminal. I have a right to avoid such charges (just as much as the airport needs to make a profit).
I don't know if Bournemouth Airport paid for the road to the terminal but, if it did it must only have been fairly recently & it can't have cost much, as when I was at the College of ATC, I remember that it was a short walk from the main road. That is where I would get out of the car.
Out if interest, do they still charge you if you simply drive up & then out again without dropping anyone off ? And if not, why not ? you are using the road too.