I’d agree that slanted beams give the music personality, and they help to show the direction of travel better than flatter beams.
However, the notion that “staff lines should never appear across an angled pair of beams” seems to be a recent one, and is not borne out by traditional engraving practice. (There are some instances of publishers erasing lines, but not many.)
The ‘good’ example that Gould gives (p.20) still shows some staff lines crossing:
(And flat beams would look very odd in that example.) She shows other ‘good’ examples, e.g. p. 24, of secondary beams angled over staff lines.
Ted Ross warns “of slanting a beam too much, or too little” (p.98). He also gives examples of secondary beaming slanting across a staff line as correct practice (p.124 & 126.) The avoidance of “wedges” that he describes is about the endpoints of the beam meeting the staff line, rather than a proscription on angled beams across staff lines entirely.
Of course, new technology means we can do things that were not possible/easy before, if they serve the reader and make the music more legible. Whether erasing the lines makes things more legible or not is still up for debate.
There have been discussion about erasing the staff lines behind secondary beams, here and on other notation websites. Also, Dorico doesn’t yet do “French beaming” (hiding the stems within secondary beams.)
@John_Ruggero to the front desk, please.