I'm with you on that.
From a creative standpoint I'm not a fan of every major character having a small army of legacies, but from a business standpoint I get why it's done and I agree with the basic principal.
So I'm not upset to see a new character brought into the Wonder-verse, because Diana is lagging behind her peers when it comes to legacies. And aside from the costume needing a minor tweak or two, I like the look of this chick (what's her name? Yara?).
But on the other hand, they don't properly utilize the two Wonder Girls they already have, the Fury moniker has mostly sat in limbo since COIE, Nubia is little more than a trivia "can you name this character?" question, and Artemis is just as removed from the Wonder mythos as Donna and Cassie. So what's the damn point of adding a new character when we've got four others who aren't being used?