Andi:
The reason that Corning Ware's Spice o' Life and Sears' Merry Mushroom were so popular was that the colors in their designs coordinated with all the popular appliance colors of the day - White, Coppertone, Avocado and Harvest Gold. You could not mis-match your appliances with either line.
Neil the Frog, on the other hand, required some decorating skill to use, because you could go wrong with it if you didn't have Avocado or White appliances. You can see that Sears did try, with some gold and brown in the design, but it still comes off as predominantly green and white.