If anything, what she's wearing is the exact OPPOSITE of what's in right now -- she's wearing a close-cut t-shirt, low-riding jeans, and minimal accessories. What's in now are loose, unstructured tunics (alternately, highly structured tops with strong shoulder lines), high-waisted, skinny bottoms, and lots of accessories like scarves and cascading necklaces.
MJ's generally been a casual kind of girl, which makes sense for someone who has to spend so much of her working life worrying about exactly how she looks, but that doesn't mean she's not up to date. Skinny jeans and a boyfriend cardigan over a simple tunic top, maybe, with a hobo bag to carry her stuff.
... Uh, it's probably REALLY obvious that I just got back from shopping, isn't it. >_>