Here's why:
* Emotional Expression: Interjections are excellent for expressing strong emotions, both positive and negative. In casual settings, people are more likely to express their emotions freely.
* Emphasis: Interjections can add emphasis to a statement or question, making it sound more forceful or passionate. This is often more effective in informal contexts.
* Spontaneity: Interjections are often spontaneous and impulsive, reflecting the natural flow of conversation. This is more common in informal settings where there's less pressure for formality.
However, it's not to say that interjections are never used in formal writing. They can occasionally be used for effect, but it's crucial to use them sparingly and with careful consideration.
Here are some examples of when interjections might be used in both formal and informal settings:
Informal:
* "Wow! That's an amazing view."
* "Ouch! That hurt."
* "Hey! What are you doing?"
Formal:
* "Indeed! This is a very important matter."
* "Alas! The experiment failed."
* "Bravo! You have given an excellent presentation."
Remember, the key is to use interjections appropriately and with awareness of the context and audience.