These edible letters have combined two simple things from childhood into one. Both irresistible. Both incredibly tactile. Both can make even a type A stop to play.
You remember those letter magnets that help kids learn the alphabet? There's something about those chunky letters --solid lines so perfectly formed that you don't just experience the letter visually, you take it in tactilely as well. It's that tactile experience that creates an immutable bond. Put those magnet letters in front of someone and they have to touch them. They'll line them up. They will spell words. Put them in order. Organize them into groups. They'll touch and they'll play.
And Jello? It is beyond human capability to eat Jello without making it wiggle. You have to do it, Jello's wiggle is an irresistible force. Just like the letters, tactile play.
Put those two things together and you've got perfectly chunky tactile letters that will wiggle for you. I must have these letters.