Why was this information released to the public?
Central banks are among the most secretive and security minded institutions known worldwide, so why make this public?
And why Now?

From this REUTERS mass media release, we are told officials/agents have and still are using an "exception in the Fed's service contracts with foreign central banks."

This does not paint a pretty picture for the U.S. agents that have this special exemption to spy on central banks.
For me, more importantly is what was discovered by seeing these non-disclosed activities - what is it that other central banks are doing that the citizens do not know?

Read through the release and note, quote: Some 250 foreign central banks and governments keep $3.3 trillion of their assets at the Federal Reserve Bank of New York, about half of the world's official dollar reserves, using a service advertised in a 2015 slide presentation as "safe and confidential." End quote.

The Bank For International Settlements (BIS) was mentioned without revealing anything useful, and went on to justify the U.S. use of this central banking spy network to respond with sanctions against Russia for annexing Crimea.

I see this "reveal" akin to throwing gasoline into the flames.
The rumors of wars, and the sour foreign relations the U.S. has with the rest of the world is already in a deteriorated state with poor, to no diplomacy - wars are likely to escalate and spread.

As awful as it sounds, that could be the nefarious motive; Wars are profitable to a few and central banks are there to fund wars. @ronmamita

By Jonathan Spicer | NEW YORK
The Federal Reserve's little-known role housing the assets of other central banks comes with a unique benefit to the United States: It serves as a source of foreign intelligence for Washington.

Senior officials from the U.S. Treasury and other government departments have turned to these otherwise confidential accounts several times a year to analyze the asset holdings of the central banks of Russia, China, Iraq, Turkey, Yemen, Libya and others, according to more than a dozen current and former senior Fed and Treasury officials.

Read Full: https://www.reuters.com/article/us-fed-accounts-intelligence-specialrepo-idUSKBN19H198