Perhaps you are reading more into the article than was there. The only graphic design of which I am critical is that which doesn't enhance the users' ability to meet their objectives. My claim is simply that before you can decide what graphic design is appropriate, you need to know what the users' objectives are. I don't see any disagreement. As for your comments about the efficacy of icons, you must be reading different studies than I have.
Icons support recognition and recall.
Except when context is limited, they are usually difficult to interpret. But no matter how interpretable an icon is, it cannot fix a problem with process. And, most usability problems are problems with process, not with icon recognition. Usability studies should not be limited to usability testing. I usually gain a lot of insight on how to organize and present concepts, how to design process, and how to express things innovatively from usability studies which look into how users perform tasks, what mental model they have, and where they perceive barriers.