The conclusion is very, very important to your essay because the challenge that you have as the writer is to conclude with strength by going beyond just summarizing your main points. Which it is included, but it does not stop short by ending it there. That would be like a dud firecracker. You have to go beyond that by creating for your audience/readers something which would cause them to take action, think about the future, take your recommendation seriously, challenge their perspective, etc. "It can suggest broader implications that will not only interest your reader, but also enrich your reader’s life in some way. It is your gift to the reader".
A: Make sure your conclusion is more than a summary of your main points, "....but don’t simply repeat things that were in your paper. Instead, show your reader how the points you made and the support and examples you used fit together. Pull it all together."
The Writing Center, University of North Carolina at Chapel Hill, suggests several strategies, however, I'll mention three of them that will help you to "Pull it together" :
1. "Play the “So What” Game. If you’re stuck and feel like your conclusion isn’t saying anything new or interesting, ask a friend to read it with you. Whenever you make a statement from your conclusion, ask the friend to say, “So what?” or “Why should anybody care?” Then ponder that question and answer it".
2. "Propose a course of action, a solution to an issue, or questions for further study. This can redirect your reader’s thought process and help her to apply your info and ideas to her own life or to see the broader implications".
3. "Include a provocative insight or quotation from the research or reading you did for your paper"
All quotations are from:
Conclusions. The Writing Center, University of North Carolina at Chapel. 26 February, 2013
I remember at NYU all the professors were and I quote: "no rehashing of the paper at the end". Once, you write the paper and assuming you made valid points, you then let the reader draw on a conclusion. No rehashing of the paper at the end once again. It's boring and redundant.
For experienced writers, your professors were correct. For a novice writer, and the wisdom of English teachers using the Core Curriculum, repeating the thesis and points is still a good and preferred practice.
Especially in persuasive papers, letting the reader draw his or her conclusions is taking a risk the point you are making will be missed. Another good rule of thumb is Tell 'em what you're going to tell 'em; tell 'em. Tell 'em what you told them.
A fine but important distinction:
We should be careful not to confuse the conclusion of an essay with the conclusion of an argument. The former is merely the final paragraph in any body of writing that we can call an essay. The latter is that which follows from the premiss. An essay need not state an argument, but an argument must have a conclusion.
I wholeheartedly agree with Leslie O. on this matter.