The Town station served the town, which when the railway was built was almost entirely on the west bank of the Ouse. The Harbour station was to serve the docks and the ferry port, which until quite recently was right down by where the station lay. The terminal platform(s) were to provide capacity for Boat Trains, which would block the Seaford line if they had to use the platforms on it. Boat Trains and ferry services were seen as a prestigious service by the old railway companies and every effort was made to pamper the passengers: no quarter-mile walk for them, even if they came in on a local train rather than a Boat Train.
Closing the Harbour station would be a long, complicated and costly procedure. Although its passenger figures are less than 10% of those of Town, the savings from closure would probably be wiped out many times over by the cost of closure. Closing stations is expensive.