Quotes are a form of RAPE! That's right, you are touching MY creations WITHOUT my consent, you can't even ask me. So let's ban the quote so that we can all have much more fun NOT being RAPED. Thank you.
It's not plagiarism unless we change the name of the person we are quoting. We are quoting directly from a person and the source is apparent when doing so. Do you ask the Wikipedia writers to use their material before quoting? I don't think so. (Wikipedia is a horrible reference btw. Just used it for lack of a better example.)
It is not a copyright issue if the original author/artist is clearly noted and the material is duely credited to them.