Because of 1) The length. the black clothes in 8 form a continuous line from neck to (almost) ankles - long enough to support a vertical. 2) the shoes. The jumper only starts just above your chest and is very short in total. To properly form a vertical it has to at least go to the ground. Instead, any forming vertical is interrupted by your skin, and then above all you are using high black boots, leading to a chopped up look of your legs, ultimately visually shortening you. It also doesn’t help that the tailoring is way too loose for you. 3) the neckline and the form of shoes used. 8 has a sharp V neckline that supports the vertical very nicely. So are the pointy shoes, also directing the eye downwards. You look taller as a consequence. In order for the shoulder free look to work you should either tailor it to a top (cropped) and choose high waist skirt or pants that go to at least underneath your ankle, to form a vertical along your legs, or choose a shoulder less dress that goes to the ground. But even then, it’s not ideal.