If what your saying is Xion was just another one of Vexen's experiments then that means she is not a true nobody, but merely an artificial being lacking a heart that it never possesed. Also why would Xion be recruited in the orginization and have an introduction but not Repliku.
Because the riku replica was a replica of Riku, who is not a nobody, while Namine is.
Namine is a special nobody, and if she was under the control of Organization XIII, I couldn't see why Vexen wouldn't want to get his hands on her...especially seeing how she's connected to both a princess of heart and a keyblade master.
I've always sort of seemed to see Namine as a creation of both Sora and Kairi, seeing how she was "created" by Kairi's heart in Sora's body, right? So would it be like,
Roxas - The Special nobody of the Key Bearer
Namine - The Special nobody combined from both the Key Bearer and a Princess of Light
Xion - The Special nobody of a Princess of Light
However -
BLAH
I am strongly against her existence, or, non-existence, er, I'm strongly against HER HAVING A ROLE IN THE KH SERIES.
I mean...it was complicated enough in the original Kingdom Hearts...but it was clear enough to feel like a beautiful fairytale - the whole scene where Sora realizes what he has to do to save Kairi, and how he turns himself into a heartless and then when she protects him he comes back and they hug...
It felt like a beautiful fairytale that was awesome and enthralling and epic...
And now...Roxas, Namine,
Xion... I could just so do without this insanity. It totally rips away from the classic and pure story of KH1, you know? Let's just break out that game again and feel relieved and reminded how we used to feel playing a KH game...ahhh.
>_>
<_<
...
I'M BAAAACKK!!!!!!!!!!!!
xD
o_o nobody remembers me.