I believe the reason they disappeared so fast from the shelves is because of an overzealous bunch of lawyers from Paramount Pictures Legal Department, out to protect unauthorized use of Star Trek merchandise/terminology. While these little minty cookies bore no resemblance to the fuzzball critters with a reproductive ability greater than a jackrabbit on Viagra & caffeine, the term "tribbles" had, in actual point-of-fact, originated with the Star Trek episode "The Trouble with Tribbles". That, apparently, was all the Legal Department needed to press the issue.