I saw another more realistic reclad proposal somewhere, but damned if I can find the article now- instead of trying to make this building look like a 3rd avenue background building, they wanted to give it new window glass (still black, not sure how reflective, or if they would keep the silver pinstripes), and reclad the crown and fins with brushed aluminum. As long as they kept it clean and didn't let it get grungy, that might actually look good!
As for the era it was built in, the early 1970's were a tough time, architecturally speaking. Too late for the height of the international style, but too soon for post-modern. Der Scutt wanted to do something other than a plain box, so he experimented with the protruding corners of the building, as well as the vertical fins and crown- At the time, International style dogma still persisted in the architectural world, and putting a (mostly) decorative stone crown atop a glass building was quite transgressive according to architectural purists.
"Build me to the heavens, and Life never stops"
"Live as if the world were as it should be, to show it what it can be"
"Prayers are fleeting and wars are forgotten, but what is built endures"
-Ambassador DeLenn, Babylon 5