So, on her it looks like style juxtaposition. I never heard it put o succinctly, but I agree with Angie. If you are young, beautiful and confident you can wear this.
The shoes say she is trying to be fashionable, too. No one wears a heel that high without it being fashion related, sweatshirt or no sweatshirt.
Now imagine this on an older woman, a shorter woman, a heavier woman, a less beautiful woman, a less French looking woman and it is instantly frumpy.
Honestly, if I saw a normal woman on the street with a sweatshirt overtop a dress, any dress, much less one below the knee, I would not think chic or fashionable.