I don't know if the MAN viewing park makes money if the car park fees (£3/hr - worth it) have to cover the costs of maintaining the planes etc. but it is certainly very popular, and definitely not just with planespotters. Perhaps someone from over the Pennines could enlighten us.
Maybe the drawback with a similar thing at NCL would be if there were enough movements to sustain interest, and obviously if there were a suitable plot of land available.