Seems like this feature is being delayed… delayed… delayed every version in your TRAC.
Personally I think this “view” should be the default one to adhere with what people expect when coming from any kind of other forum softwares (which also makes more sense to me regarding the visual organization of a forum).
Also the “per forum permission group” thing is a must in the core of any forum IMHO. There is no way to manage big forums like mine without it, where we have mod groups coordinating different sections/aspects of the site.
But again this is just my personal opinion.