There will always be bullying. That's how kids grow up. It's part of their learning of social skills, however cruel it can be.
IMHO, the point is that once you let iPads (or any tech-device) be the communication device, it gets much harder for the teacher to react to that bullying.
Give an (lower-than?) average student of early teenage years an iPad in the classroom... of course he will try to find porn sites, send outrageous messages, and play games instead of paying attention to the boring teacher. It's cool to do that, right?
The average teacher has no idea how to stop that unwanted behaviour. He probably goes to the IT department and starts complaining there. And then what? Use Mobile Device Management? Force enrollment (DEP)? Make it the IT department's problem?
I think the usage of such devices at school is generally a good idea (21st century skills etc.), but the way they should be implemented at schools is simply not well thought out, yet.