True. Naked witch is naked both metaphorically and physically, not even bothering to hide from police.
Gyaru is the chosen because she's a master of outward faces, and both girls are interested in the magical girl as a separate identity in and of itself. A theme that fundamentally requires both an actor and an audience to explore, which is why there are 2 MCs.
The symbolism of using a Kigurumi as the transformation item/sequence is also great, as well as Shiki's love for Sweet Pink vs her avoidance of the gyaru version.
Not to mention I have high hopes for the story exploring the usage of socially acceptable Public Faces vs needing to be honest with yourself. I've read many stories that deal with the "need to be honest with yourself" part with Hero's Journey and YA-type novels all having parts of this, it is actually quite rare to see a story presenting the necessity of the Gawa (Tatemae?) as a social lubricant.
You can't just ignore society after all, I hope this story doesn't go down the usual path. It's a topic the story can have lots of fodder for plot and character development.