Thanks for that, actually! You're the first to comment on the aesthetics rather than the "incorrect" usage. My thinking is that the dashes are part of the pragmatics of the primary, wrapping phrase, and don't actually interact with the inner one—they are therefore bound to the first and separate from the second. Whether or not it's a good look, the fact that doing so much better signposts the parenthetical makes it worth it, right? And that spacing rule is actually almost the same as with ellipses, though I'm definitely with you on that taking a while to look good to me as well.

Do you think it's just being unused to that layout, or is there some deeper issue to how it looks?