I'm watching Bleach again from the beginning to get ready for the TYBW arc, and out of all the VCs, it looks like Renji, Ikkaku, Hisagi, and Rangiku had the most potential. In the SS arc, Rangiku beats Kira with not injuries, which would put her in the higher end of VC-level. AT this time...
www.fanverse.org
You can't waste what wasn't there to begin with. She's only in the story at all, as a motivating factor for GIN'S actions. She solely serves to motivate another character and doesn't really have anything to work with in her own right, that one could waste.
They can deny it all they want, but ultimately the only reason Rangiku's popular is 'cause she's hot and they just want to pretend she had actual character so they can hide that fact.
I think Nanao's the hottest character in the series, doesn't mean I'm gonna sit and pretend she was more interesting or added more to the story than she actually did. Ultimately she was only there to be protected and to eventually provide a dues ex machina for Shunsui to beat Lillie with.