Seems like a the dimming is a solution to a problem that didn't need to be solved. The module action buttons should be in the same neighborhood as the module, so I don't think it is necessary to notify the user which module they are editing. Unless you have a lot of small modules stacked in the same spot, but even then i don't see the dimming helping that much. Overall, I really dislike a lot of the UI changes that occurred in 7. I always turn the ribbon bar on and dimming off. Maybe new users who don't have the background aren't as annoyed.