When making personal threads, from what I can remember Staff saying, the person making the thread has the option between GC and EoEO. There's no definite rules between them, except that a thread made in EoEO will have significantly less spam.
Now, why isn't this the same for EotW? When making a thread about current events, if the person making the thread considers the topic to be more light-hearted discussion, why can't he/she make it in GC? And if people start to discuss things more seriously, so what?