They all seek the Tesseract for it's a source of unlimited sweetness.
Imagine waking up on Sunday morning after a super fun night out on the town for your friend's birthday. You're exhausted, you're sore, your voice is hoarse from proclamations of merriment, your hair smells funny and you still have one sock on. Now imagine that this donut appears on your nightstand. Feeling a bit better now? I thought so.
Sometimes you only want one little cookie. Sometimes you only want one little hard peppermint. I think this philosophy stretches across a lot of disciplines. Sometimes you only want one little cup of coffee, kiss from the dog, shot of tequila, chocolate on your pillow... I could go on and on.