The tearing of Janet Jackson's costume was unrehearsed, unplanned, completely unintentional and was inconsistent with assurances we had about the content of the performance.
The costume was obviously designed to tear away to reveal precisely what was revealed. The "tear" is just too neat, too improbably made through tough fabric/leather, and too well-targetted. And what's with the giant metal attachment?
I do believe this part of the apology--or, I mean half, of it:
MTV regrets this incident occurred and we apologize to anyone who was offended by it.
Basically, that is: we want those who were offended to still like us. Of course, if no one were offended, it wouldn't have been worth doing.
UPDATE: On reflection, I realize that there are plenty of reasons to do it if it didn't offend anyone! One reason to do it is to shock and surprise, but if it didn't upset anyone anymore, obviously, plenty of people would enjoy seeing an exposed breast and some people would be interested in the fashion innovation.