Rationalizations of my earlier rough observations

Q. Why should borders that seem to need round corners be eliminated?

A. Round borders serve to make visually overcharged borders less overcharged. But the symptom of overchargedness is better dealt with by eliminating the problem altogether -- get rid of the borders -- or tone them down, for instance in the border around a pop-up menu. (But I think one should not put borders between the entries in a pop-up menu.)

Q. Why not use boldface?

A. You don't need that much emphasis. There are exceptions, such as the alphabetized word entries in a dictionary; these need to stand out greatly, to make them easy to find by scanning. (The coming era of embedded webfonts should make it easier to use small caps as a second level of emphasis, above italics. Unfortunately, DA journal CSS doesn't allow @-rules, unless they've changed that.)