I would say that it's only an addiction if it's actively interfering with your normal life. That is, your job, your education, your family, and your interpersonal relationships.
I don't use IM'ing and texting as much as I used to (in college) but I still use it. I don't think you can really call these addictions. These are just different forms of communication. I just think they might be overreacting a bit. For example, the comment from one of the students about being secluded... one would feel the same way if they were told not to talk to anyone.
Now if they were whining that they couldn't chat when they were hanging out with their friends... that might be a problem. I think chatting and texting augments social interaction. The problem is when it turns into a substitute. So I'm not saying that internet/text/chatting addiction doesn't exist -- we just have to be careful about defining what internet addiction really is.