Understand the concern of your question, but having a rating system would seem somewhat judgemental, labeling, and subjective in nature.
To have a rating system of some sort would kinda defeat the true nature of aikido!
Not that I profess to like "dancing in the dojo!"
I think it depends on many factors. I study in a dojo where some people dance and some people don't. To me it is really an individual concept, not one to apply to a dojo as a whole.
However, done correctly, Aikido can be a very beautiful, soft, flowing dance.
My goal is to have my aikido become just that. Doesn't mean I am less effectively martially, infact it mean I probably am more so!