Hot topics is designed for rabbit related debates that are a bit controversial and have a tendency to get heated - things that are relevant to the forum and rabbit owners but need extra attention from the mods. Most of those are related to welfare so it sits in there.
General chat is for a friendly chat on non rabbit related stuff. If you get heated in there it will get locked. Every post in the hot topics section needs to be read and approved by a mod so I don't think it's fair to create extra work for them so people can have heated debates about politics or religion etc. - there are lots of other forums on the web if you wanna do that