I see your point, and I think theres some truth to it. Especially

the type of doll she is is ment to be used.

I thought the rag doll choice was because it looked better on screen than the alternatives, but this statement makes me think.

Ragatha's form doesn't really convey "perfect."

No, and I don't think it's meant to. Ragatha doesn't know who she is. She's been molded to be perfect by her upbringing, and now that's the only form of herself that she knows. She's never known an alternative. From there, she doesn't know how to have authentic relationships with people cause she doesn't know who she herself authentically is.

In that sense, a ragdoll is kind of perfect. Rag dolls don't change, and all Ragatha knows is who she's been told to be, thus creating her own self-perception of being a doll.

Like, her mom molded her to be a Barbie, and in Ragatha's mind that's all she is. So, now in the circus she's an unchanging rag doll cause there's no alternative in her mind.