It surely doesn't help Air Tahiti Nui that everything in French Polynesia is so incredibly expensive. I loved our visit to Moorea, but I can have a pretty similar experience in Hawaii with a great deal less travel time and lower cost.
Part of FP's high costs stem from its remote location. A very big part, though, is the taxation and other French-style regulation. I'm happy for the janitors who earn a comforable living with all of the benefits of the French welfare state, but this sort of thing is making FP vacations very costly. They are not the only set of beautiful Pacific islands, and tourists are passing them over in favor of other less expensive holidays.