My point is that Manhattan is on the right track, it has a high population density and amount of apartment units per square foot.

There are many other areas that are prime for development, where it would be much easier, faster and cheaper to do it. Keep doing it in Manhattan, but do it elsewhere too. There are areas within 40 minutes of Midtown with the train that are basically ghost towns throughout, and instead people would push hard to put something up in Soho, which as-is is already overcrowded, dirty where the infrastructure cannot keep up with all of it.