Forcing the user to use a significant amount of screen real estate to edit the attributes of objects. Having to click the different "tabs" in the edit area, with the remaining area unused, when it could be utilized to display other controls and attributes of the object. It just seems like a lot of user clicking is involved when the tools could display their values in a tiered drop down when necessary approach. I am no programmer, however, I am a 25 year veteran in using graphic applications. Some interfaces are elegant and intuitive, others not so much. Inkscape is so close to being the former.