This forum is lacking a dedicated forum section. In the last days I have seen lots of great discussions about world design, which were all completely off-topic, since there is no place where you could start threads about them.
We used to have such a forum, but it did not get enough traffic to justify its existence.
If you are talking world-design that's strongly linked to a particular rule-set, then such a thread should be in the forum for that rule-set. If you are talking world design suited to many rulesets, or that is completely rules-agnostic, then it belongs in General, as they are, well, general, rather than specific.