That first chick looks so amazingly uncomfortable I laughed aloud. Also, structure in clothes is exactly what pin-up style has a lot of. Military-inspired clothes also have a lot of structure. That first girl's shirt and the second girl's harem-pants romper thing do not. The latter is floaty because of the fabric it is made from, not because the design is inherently ethereal, and the former is just frumpy. The skirt would be pretty ok if it wasn't too short for her chicken-legs. Edit: I said too short, maybe it is the wrong shape? I am not sure, but it isn't flattering. It makes her thighs look skeletal.
I like the jacket in the third picture, though. It is pretty cool.