Manhattan, being one of the world centers of capitalism, is a tiny island thirteen and a half miles long and two and one-third miles wide at its widest point (around 14th Street). Its geography creates a natural demand for space. Any space, anywhere. Because of this, there is a psychological shift toward great material needs of all kind. The competition for space is so severe that prices for most items, especially housing, are driven into the stratosphere. Because it is also a draw for second homes for the wealthy of the world, the prices soar.
If there were no East River so the island became part of Long Island to the east, everything would have been cheaper. Spaces would have been built larger. Wall Street workers would feel less like rats in cages who were in need of more space. They would panic less. They would possibly be calmer and more responsible. The east side would have been enormous.
I say, for the sake of world fiscal stability, fill in the East River and let Manhattan roll effortlessly into Queens and Brooklyn as one land mass. Please.