The plants are almost an architectural feature--a refreshing touch of whimsical elegance in a prominent area that's most visible to visitors to the city. If there isn't uniformity to the plants, then the choices should be controlled, perhaps with the guidance of an architect or landscape designer. Random plants along every balcony will look inharmonious.
On a less serious note, one phrase that comes to mind in seeing the rows of balcony plants decorating this high-rise is "New York run by
the Swiss".