I think that allowing all editing features to be performed on multiple pictures within either an item or a list at the same time would be amazing! It does not necessarily have to be specific to photo rotation. I just noticed that photo rotation was one of those things I was spending a bit of time on.
However, I would prefer to select individual pages within an item and/or list for this mass editing, as opposed to the entire item and/or list. Some days I pull 2000+ photos from an archive, and I seem to have rotated my cell phone camera at random intervals. Half are turned one direction, and then half in another (on a good day, more often than not I rotate every 40 or so pages). This mean that in one document, I could have things turned in all four directions. Thus, it would be easier to use a shift or ctl + click function within items and lists.
Speaking of editing, another neat editing feature would be adding a deblur function. Right now, I use an app on my cell phone for this, but it is a bit time intensive.