Soviet-era polka dots

I have been seriously crushing over these Soviet-era polka-dot kitchenware designs of late. The red I understand. But can anyone tell me what was behind the polka dots?

{Image links - all on Etsy: 1. milk can 2. tin canisters 3. enamel pot 4. tea cup 5. vintage clock 6. ceramic pitcher 7. sugar bowl & creamer 8. coffee cups 9. tea pot 10. square canisters 11. porcelain bowls 12. enamel cups}