The thing to understand about the change in policy regime that led to the elimination of the reserve requirement is this: banks were (and are) holding massively more reserves than they needed to. They didn’t need the Fed to tell them to do this, so it was not an effective monetary policy tool any more.

In economic terms: the supply of reserves was so high that it was in an inelastic part of the demand curve for reserves.

The new regime (“ample reserves”) depends on administered interest rates, rather than reserve requirements, to set short-term interest rates.

It is absolutely not the case that the reserve requirements were removed to allow banks to reduce their reserves.