I don't see the point. I'm a german speaker, but if people stick to one language on the internet, more people can profit. I don't see any problem with people talking in their respective language in a single thread (like the delivery in germany thread) as other people will hardly care about the content.
With subforums it's mostly the case that people who can speak English well will just use the English forums for their questions, announcements, etc. because there's a greater audience, while only a few people who don't want to bother writing in English will use the subforums. language specific forums are usually a very boring place to be.
