I think it would be a good idea, to seperate rights for posting per each group, but by default its set the way it is now, but what you can do is only allow Moderators to post the bbcode, or certain bbcode in a post, this way it stops the spammers that are new members from posting stupid stuff.

There could be other reasons in itself to make the IPB board by default like this

So, in other words, only certain groups could access such BB as URL and IMG? That seems like a nice option to have. That way spammers who registered wouldn't be able to post direct links. :)