My argument is that the foreign tourists who visit these places would be visiting NYC either way, and are just visiting these sites
while they're in NYC, with something else having drawn them there. These sites are serving as part of a portfolio of factors that make NYC an interesting place to visit, but they don't manage to draw tourists
all on their own in a way where reducing the ticket price to them would make a foreign tourist
more likely to book a flight to America as a whole, just to go to NYC, just to go to that site.
Consider the "gap-year" 20-something who "travels Europe" by just staying in each country a few days to visit the cultural sites while staying at a hostel. To such a person, the equivalent cultural sites in the US are basically inaccessible. (Not that such a person is the sort of high-hospitality-ROI that a city would plan around; but their presence as a "keystone species" indicates that a hospitality-loss-led economy is functioning the way it should.)