Models are really skinny so they won’t be sexually attractive. Otherwise, they’d distract attention from a designer’s clothes.
Designers may not consciously be aware of it, but that’s how it seems to me. Here’s why.
Across cultures, whether status comes from being slim or big, the “hourglass” shape is the preferred sexually attractive form for women. If a model is hyper thin and sticklike she’s eliminating any focus on her and keeps the focus on the clothes she’s wearing.
When glancing at this woman on her way to the beach, you probably didn’t initially take in that she’s wearing a polka dot white bikini and an orange swimsuit cover-up.
Visual stimulation is key. We’re aroused by arousal. It’s complicated.
Here’s an example from one part of the sexual spectrum, heterosexual men. Most of the time, straight men watch porn featuring men and women. Men seem to be aroused by seeing another man on screen who’s aroused by the woman he’s with. Sort of, a non gay, penis appreciation. If this wasn’t the case then straight men would generally prefer to only watch lesbian porn, with no men in sight. It’s complicated, right? But the visual component wherever it falls on an attractiveness spectrum is always there.
Because skinny models remove sexual interest from the models and puts the focus on the outfit, designers fuel the market for skinnier models. That’s probably oversimplifying the situation, but I think it’s a big part of why models are really skinny.