I agree with a lot of the points. After doing some of my own lens testing, I realized how easy it is to miss the perfect focus just enough to make a big sharpness difference. Or at least something you can see in a 100% crop. There is no way that I am that careful using a lens for a real photo. That especially applies to the sharpness difference between something like my Pentax-A 50mm f1.4 and Pentax-F 50mm f1.7. I might be able to demonstrate it in a test but in real photos, it's all about where I focused.
Still, I wouldn't ignore sharpness as one part of performance. It helps to know where your lenses are not that great. It's useful as a sorting tool, for those of us with high LBA levels. I think Rockwell overstates the quality of modern lenses
if you include the consumer zoom category. Those are compromise designs, and the designers may have compromised sharpness for something else. Also Rockwell gets to handle all the lenses, so he can talk about handling differences, while today the typical person gets a lens on Amazon or whatever. Should the typical consumer order each 17-70 just to see how they feel, or maybe look at sharpness to get an idea of overall quality?
Recently I started to like a few unsharp lenses. Here is a long post about one of them:
Sears 28mm f2.8