S.F.L.Y - you must have missed the information from both the Preliminary Report and flying basics that reducing the flaps was aimed at reducing the drag when the power become lost.
You have correctly noticed that the speed control was critical and reducing flaps was aimed at maintaining the speed and the lift required to keep a/c in the air. This helped to keep the a/c aloft just for a few second longer but those additional seconds had tremendous influence on the final vertical speed.
The plane was flying and not falling down practically until the end. Final descent rate was about 1400fpm but if the plane kept flying just 3 sec longer it could have been at least 2x bigger with fatal consequences. See the diagram on page 6. Check basic physics.