It would certainly be interesting as an exam question, for example, to compare 2D and 3D for what it would reveal about each, but in the end it's all about choosing an appropriate model for the task at hand. I'd therefore suggest that pitting 2D against 3D is actively choosing to set up some kind of battle that doesn't actually exist in reality - most of the time there is nothing to be added to an analysis by choosing to store data in 3D, and 2D simplifies all parts of the chain i.e. capture, storage, processing, output etc. I'd strongly reject the idea that but for resistance we'd all be in a wonderland of 3D GIS. People in industry just pick the best tool for the task at hand, and that's almost always 2D.