Constant upkeep

All the cornices and stonework etc. require a lot of upkeep all over New York City.

Many buildings built before World War I had really fancy cornices. These started crumbling back in the 1970's as I remember and a lot of buildings had them removed completely, which drastically altered the appearance of the buildings.

From internet article on this topic:

Most New Yorkers are too jaded and too hurried to look up at the often stunning architecture that surrounds them. But to some, like Mr. Bess, who do, every building with a top denuded of pressed tin, copper, cast-iron, stone, terra-cotta or even wood cornices and ornamentation stands out like a disfigured part of the urban landscape.

Many of those naked tops are the unintended consequence of Local Law 10, passed less than a year after Grace Gold, a Barnard student, was struck and killed by a falling piece of masonry at 115th Street and Broadway 25 years ago last month, and of its even more stringent successor, Local Law 11, passed in 1998.

The law, which requires that exterior walls and projecting ornamentation be inspected for safety by an engineer every five years, applies to the 12,000 city buildings - 60 percent of them in Manhattan - that are taller than six stories. Preservationists say the laws have contributed to the attitude that old buildings are inherently dangerous and should be stripped of decoration as a preventive measure rather than take a chance that a piece of masonry or cornice will fall off. As a result, ornamentation may be removed independently of the facade-inspection law, as was the case with the building on Strivers Row.

The neighborhoods most affected are often long-neglected jewels like Harlem and Fort Greene, Brooklyn, where the architecture is beautiful but ill-maintained, and where building owners are more likely to comply with safety requirements by taking the cheapest route instead of the most aesthetically pleasing one.

It is hard to miss the evidence of destruction wrought in the name of safety. Lintels have been shaved off windows, leaving behind a flattened shadow of the former ornament. Apartment buildings have been capped by ribbons of "ghosting," layers of bare brick or stucco parging where massive overhanging cornices once hung like beetled brows. Such ghostings can be seen along Columbus Avenue in Manhattan Valley. Buildings have been scalped on nearly every block of Lenox Avenue in Harlem.