Why are Japanese glyph variant of HYPHEN, EN DASH, EM DASH important for us?

Hello Nat / Yamamoto-san,

Why are Japanese glyph variant of HYPHEN, EN DASH, EM DASH important for us? I believe we discussed it once in the past (e.g. https://github.com/w3c/jlreq/issues/276) but I would greatly appreciate it if you could summarize it in the issue below.

https://github.com/w3c/jlreq-d/issues/69

Thanks!

- kida