Sexting? A ridiculous practice that erodes our writing abilities. How in the world am I supposed to properly describe the depths of the lewdness and depravity in my intentions with my partner with nothing more than a 160 character limit? That's not even enough room to agonize over the details of my beautiful new leather restraints. The best they could expect from a text is "Check your e-mail, I have sent you several paragraphs." Close that dang phone and open up some sort of writing program, if you can't fill half a page then it's not worth sending to your lover. This is your new homework.
More seriously though. I've never had any real issue with the practice. I have partaken myself, always with someone I have had unending trust in. I never sent pictures of myself, though I have had them sent to me, and I have never let them out beyond my own personal viewing (At this point they are all deleted forever). It's fun. Nice, clean, dirty, enjoyable fun. I think healthy, consensual expression of sexual desires in a safe environment is a very good thing, especially for those who want to be intimate but aren't yet comfortable with the idea of physical intimacy. However a person wishes to express their sexual desires with another is fine with me, as long as it is consensual.
I think the danger right now lies in the fact that it's a relatively new practice that people are still squeamish over, and as such there's much less urging for safe practices with it. Unlike normal sex education, there's not enough insistence over discretion, urging to not let yourself be pressured into partaking, and how to put an end to it if someone is sending texts and pictures to you unwanted. It would also go a long way if we could do more to put our foot down on these disgusting 'revenge' porn sites and other sites that collect photos and videos of women without the subject's consent to them being posted.
Having actual tangible pictures and words floating around about what you've done is certainly a scary prospect, and that should be known. However it's not like we've never had to live with scumbags who are willing to use their sexual conquests as a means to blackmail and shame their partners. Ultimately I feel the important thing is to do more to create an environment in which someone who is the victim of this behavior does not feel unsafe about reporting or talking about it. Otherwise, proper education, laying out the information a teen needs to make a proper and informed choice of what they want to do and the potential consequences is the best option.