Go on the Apple app store and search for "lemmings". I found quite a few games that were all based on this premise, the biggest one being "Flockers" by Team 17 (the same people who made "Worms").
It may be! My belief stemmed from the fact that I've heard of no break-out success herding games besides Lemmings itself. Nobody has gotten rich by making a herding game. There is no herding game with merchandise. Etc.
Maybe it's more popular than you realized?