Why don't they just say "매우"?

I have been studying Korean for a long time, but I still find it quite difficult to understand a group of young Koreans engaged in excited conversation, and one of the reasons it is so difficult is that they love to use slang. Here is a good example.

The word 매우 is a nice Korean adverb that means "very." I like it, but, for some reason, young Koreans seem to hate it because they have invented all kinds of slang expressions to replace it. Here are a few of them:

• 대따
• 대빵
• 되게
• 디따
• 딥따
• 억수로 겁나게
• 억시기
• 열라
• 짱
• 절라
• 존나
• 졸라
• 콜라리
• 허벌나게

I hate Korean slang because I think it is hurting the language, but I especially hate slang that replaces nice Korean adverbs.