My understanding of the law on this is fuzzy, so I'll just address the ethical aspect.
I think people have a poor understanding, in general, of exactly what is wrong with plagiarizing. These are probably people who thought nothing of finding someone else's book report or term paper on the internet and handing it in as their own when they were in school.
When you take the product of someone else's creativity and labor and claim it as your own-- writing or images-- you're misrepresenting yourself and doing a discredit to the person whose work you're ripping off. Personally, I don't see a problem with presenting someone else's work if you attribute it as such, and in fact many people find it highly gratifying to see themselves quoted by others or their work shown off by someone else....so long as that "someone else" isn't pretending it's their own or profiting off of it.
I have written articles, essays, and two theses and would be absolutely livid to find out that somebody had copied from them and claimed it as their own. Sorry if you're feeling to lazy to write that final essay for your college course-- that doesn't make the product of my long hours of research fair game.
