But why was it drivel? Is it any more drivel than Canon's ineffective dust reduction system?

Seriously though, the whole idea of the pattern was that it provided the same light reflectance as film, so it didn't matter whether the light sensor read from the film or the shutter curtains.

It is much easier (and more reliable) to produce a black shutter curtain with a white pattern on it than a grey or brown shutter curtain, as it is more likey that light reflectance will change during its working life.

The pattern is required so that reflectance (as seen by the sensor) remains consistent throughout the shutter travel.