I guess, compared to other sports, it should be considered a sport. But it shouldn't be an olympic sport because it isn't strength centered enough. (The original olympics were meant to be strength centered.)
That being said, rythmic gymnastics is still very beautiful and creative. Now I'm starting to think of it as an art form, not a sport.
I don't know for sure. I can't decide. But you can only go so far with it. There aren't any very very hard skills, compared to artistic.