The reasoning behind this specific design choice is a bit unclear, but here are some possible explanations:
* Visual Contrast: The white dots create a stark contrast against the yellow, making Mickey's shorts stand out more and improving visibility in animation.
* Childlike Appeal: The dots add a playful and whimsical element to his appearance, which is appealing to young audiences.
* Design Inspiration: It's possible the design was inspired by real-life clothing or patterns popular during the early days of animation.
Ultimately, the iconic design of Mickey's shorts, including the white polka dots, is just one part of what makes him so recognizable and beloved around the world.