Be careful when "going for the throat" as you could come across the wrong way. We almost turned down one engineer because he seemed insecure and hot tempered, but the reality was that he was just anxious about the interview and having his credentials questioned. He turned out to be a mature, nice guy.
Usually peoples negative qualities cost the business money.
If you can simply demonstrate that you understand how to provide the business with value then you're miles ahead of 99% of other candidates.
If anyone doubts this, go ask people who do sales how they answer this question. Great sales people in interviewes will already have a calculated dollar amount in new revenue that they're going to bring to the business.
My whole resume is presented as projects I've done that generated real value for the business. My interview and offer rate is above 50%. It's not rocket science.
Another option is "Because the rest of your candidate pool won't generate the value that I will and it's a business risk to allow a competitor to hire me."
I wouldn't use this answer fresh out of college though. Instead I might go with "Because I'm more capable than my graduating peers for X, Y & Z. I'll give you better bang-for-buck over time than other new grads and mid-level candidates in your pipeline and you don't have to pay anyone a recruiter fee."
Go for the throat. Also nobody gets this level of confidence/honesty/awareness in response to these questions, so at the very least you will stick out.
Make sure it's a check you can cash though.