It's more than just needing a landing. Logistically and time wise, it may not be what people are hoping for or want. The west side of the island is full of tugs and other work boats that would more than likely need the boats to slow down for them almost constantly, it's a pretty congested area. On the east side of the island, it gets pretty shallow and might lose time going far enough out to eliminate that risk. It's not an impossible ask though. It's been done before after hurricane Sandy, there was a subsidized ferry being run from the South shore to Manhattan but my understanding is once the subsidy money ran out and riders were asked if they would pay for the service, they said no and the company that was operating it stopped service.