As a form of protest or whistleblowing, anonymity is absolutely useful. Wikileaks needed anonymity to really work, and Twitter users in Turkey reporting on unrest there see the need for anonymity.
The problem is that while you could conceive of a noble purpose, very few people are going to use it for that purpose, least of all US high school kids.
Letting kids be terrible to each other so that they can see first hand how it unpleasant it is. Through that experience they will become more compassionate adults.
The problem is that while you could conceive of a noble purpose, very few people are going to use it for that purpose, least of all US high school kids.