A GOOD inker - like Joe Sinnott or Mike Royer - added to Kirby's pencils and accentuated their finer qualities. They gave depth and life to his work, making even his worst-written yarns sing on the printed page.
However, a bad inker - like D. Bruce Berry in 1st Issue Special #1: Introducing Atlas - sucked the life out of Jack's art and gave it a flat, bland quality.
Basically, Berry appears to have erased half of Kirby's pencils to make his inking job as easy as possible. The result: a piece of hackwork that can't save what was already a lacklustre yarn about Atlas, the first king of Atlantis.
I'm certain it was Berry's inks that led to Atlas not being given the green light for its own series, thereby robbing us of yet another gods-filled universe by Kirby.
(So maybe that was a good thing...)