Naoko is a huge figure skating fan. Her manga series before Sailor Moon was about figure skating. The figure skating episode of Classic was inspired by her love of the sport. When she first met Evgenia a few years back, she gave her an original illustration she made just for her. It is not surprising that Naoko would use figure skating poses in new cover illustrations. Maybe she was inspired by the ice show. Maybe she drew these covers with using them to promote the show in mind. (I mean, this franchise has never met a picture it didn't recycle ad nauseum.) But the idea that these illustrations were drawn *specifically* for the ice show and are now being used as cover art instead - especially because Naoko's "too lazy" to draw new ones - is absurd.
And like....yeah, the unfinished legs are really weird, but it's not exactly the first time Naoko's illustrations have featured unfinished bodies/legs/arms. It's just the first time the unfinished limbs have been so obvious.