One of the most powerful learning tools is dictation or copying. This is like pagiarism- except the work is not represented as one's own. I think we expect too much sui generis from children, without giving them adequate models of what we want. Children should be copying out great writing as soon as they can write- so that they can internalize the rythms of our language, and produce original material when they are older. I cannot imagine wanting to steal ideas, if you had the tools at your disposal to produce really fine ideas of your own.
I am very sad for the high school students who felt they needed to plagiarize. I borrow all the time from great writers, and from other teachers, but I always credit the people I am borrowing from. I hope we learn to teach students how to write their own ideas better, and how to borrow gracefully and while giving full credit. All the great writers borrow, and all the great writers use other writers' ideas as springboards. The trick is to teach that. This is not, imo, a moral problem, so much as it is an educational problem. The same people who will wail and gnash their teeth about this (I stole that from the Bible, btw) will fail to see that the emphasis on teaching to standarized tests to improve "accountability" has led instructors to rely more and more on bubbled in scantron tests, and less and less on written work- which is generally not tested on these standardized tests. There are no easy answers, there are no perfect villians, we live in a complicated world- and the biggest fools (imo) are the people who fail to recognize that.