I agree it would be a good idea, though as the moderators seem to be quite busy they may not have time to handle such a new section...
Unless we, users of this site, find a place to host WIP and exhibition movies i do not think it would be (for now) a good idea to add this section to the site... Look at the submissions page, it has submissions that have been posted last year (2004)...
So, one of us should make a page to host WIPs and things like that and then ask Bisqwit to make a link of this new page on the site...
Unless (n°2) that Bisqwit agrees to make such a page (and if he does... good luck to him)
I guess that even with tools, perfection is not easy (Copyright Bisqwit)... And nOObs post their unperfect movies to have a feedback on what they did (and because most of the time b/c they're nOObs and so they do not know it's unperfect)...
Because an exhibition page does not exist and because it's much easier to find the submission page than a certain topic on the forum, they post it in the submission page...
But I encourage newbies to try TA, it's hard but the result is worth being seen :)
*Edit* : Note that I do not say that I'm experienced, though i think that I now understand quite well how movies are made...
In fact, a system for WIP movies is under construction for this site.
The submission queue will eventually be converted to some kind of project manager.
However the schedule for that project is not yet established.