Why do Koreans exaggerate their mouths?

The relationship between folk customs and pronunciation, folk customs, such as eating noodles, we are generally used to eating quietly to show self-restraint and respect, but Koreans should suck loudly, the louder the better, indicating that the noodles cooked by the host feel delicious and can't wait, giving us an exaggerated feeling. Secondly, the pronunciation, because the pronunciation of the tongue is different, the pronunciation of Japan and South Korea depends on the back of the tongue cavity (a bit like the feeling of short tongue, no insult), so the external muscles of the face are different from ours when speaking, so I feel that they speak slowly and their expressions are exaggerated.