Don't see evidence she can use the Tailed Beast Ball... it's not an automatic thing, and Yugito was not a fully attuned host. Until she proves she can use it, she can't (and no, Obito controlling her to do it doesn't count). There's a reason we're told only like 4 people can truly be said to have controlled a tailed beast (Madara, Hashi, Bee and maybe Yagura... though really Yagura seems to have been thanks to Tobi), it's because most of the time the hosts gradually lose control until they become incompatible and the beast goes beserk. Until proven otherwise, Yugito was just another in a long line of failures.