Wow, seems like I've discovered this forum too late! :)
I'm a Communications Studies student with Nanyang Technological University in Singapore. I'm about to complete, for my final year project, a research paper on IRC using the Uses and Gratifications theory.
I was an IRC addict two years ago. During that time, I ran into some problems due mainly to bad time management. That spurred me to do a research paper on the consequences - both latent and manifested - for a term paper. Then I thought about the motivations behind the use of IRC, and so went on to this current paper applying the U&G theory on IRC.
I believe that other than personal factors, situational factors and characteristics of the medium are equally important in influencing a decision to IRC or not. For instance, a shy and less vocal person may have an unfulfiled need to gain listeners. With the anonymity and no physical contact characteristics of the medium, if given situational opportunities like an access to the server, he/she is more likely to want to engage in IRCing. And whether or not this need is satisfied, to what extent it is being satisfied, will determine subsequent continuation or termination of IRCing.
I've been looking real hard for academic papers on IRC but haven't found much. Oh well.. anyway I'm going to hand in my paper real soon.. Just hope there'll be more research done on IRC in the near future. :)