The removal of grooves from the driver was to allow for a stronger face as they made them thinner.
Grooves themselve add very little spin. In Search of the Perfect Swing, they discovered that the smooth face club actually had longer distances, (5i about 5 yds, 9i about 2 yds) which appear to be a result of the less spin on the smooth face.
Now out of the garbage, the biggie was that the grooves allowed for the ball to make more direct contact with the actual club surface.
The square groove arguement I thought really ended up centering on the width of the grooves cause it was creating a surface which dug into the balls surface far more than other clubfaces.
Threaded Mode
