Edit Original in context menu Placed image
Just like other CC applications, Ai should offer the possibility to open the source of a Placed image directly from within Ai. (Photoshop most of the time).
If you have Control panel displayed, there is an Edit in Photoshop button there.
If not — there is a 'pencil' button that does the same in Links panel.
But there is none in context menu, here I agree.