Yeah, ive made the request a few times before myself. Im sure they have their reason, but im also hope it shoudlnt be to hard to figure out how to make it possible. of course i could be completely wrong
I have a theater view skin athat allows me to browse my photos and see them in a large now playing window on the same screen as my browse list (Much like Gappie's set up if you seen his posts on his skin), but setting it up so that works ruins movie playback and audio if you use any specialized full screen display plugins. If able to configure spearately it would let you script the view so that on movies you could have a very clean thumbnail view, and when you launch a film it goes fullscreen (as youd usually want I'd think), any audio file would allow you to have its vizualization also be fullscreen (for those who want it, i do as i use the awesome audioscrobbler viz) and would still allow you to have your photos work in a split screen theater view style.
Another completely workable option would be to allow for now playing behavior to be scripted in the theater view script itself, say in the page description being able to overraide the "jump on play" behavior for that individual page. that would actually be perfect, but i cant see how that would work currently.