User blog comment:FairyRaven/Fairy Tail Chapter 324: The One Who Closes The Door, Review and Commentary/@comment-4999650-20130322193315/@comment-84.113.52.218-20130322200947

It's far more interresting to have a counterpoint character to future Lucy, with another plan. Maybe even someone who can be seen as a "bad guy" a bit.

Yukino fills neither of those roles well, since she is far too much like Lucy, which would just make her redundant, unless she underwent a total character makeover...