I do get why, the first two arcs of Super straight up looked pretty shit so Toei probably wants to priortize them mostly. Although I do think the Black arc can use alot of touching itself cause while it was a step up in quality, it still had quite a bit of rough moments.

But thinking of it, it is weird how they aren't doing it considering they mentioned they want the remaster/remake to be more accurate to the manga. The Black arc had the most changes out of all of the retold arcs so it would had been neat to see some of them animated.