Question

Why do writers use appositives and appositive phrases in their writing?

Answer 1

An appositive renames a noun. It can be long or short. For example
She ate the fruit, an old banana in which i did not want.
So, she ate the fruit didn't really explain much, but a banana renames it. Writers use them to (I think) add more emphasis and detail, because she ate the fruit sounds like a mere bore. Why put a boring phrase when you can add so much more element to what you are trying to say? :)