Compromising your viewpoints and behavior is bad generally: it will in the end only lead to frustration and will be a hindrance in achieving one's goals.
There are many situations in which compromising the viewpoint is bad, and one of the is an interpersonal conflict: it might solve the problem in a short-term, but not in a long term.
Answer:
1: Taking a sentence from a book and not stating the author.
2: Copying someones essay or test.
3: Taking a definition from Wikipedia and not stating that you got it from Wikipedia.
To create a better image in the reader's mind. The use of imagery creates a better picture when the reader imagines the setting. Since when reading everyone thinks of a different picture imagery helps to create a picture closer to what the author imagined.
