@SaffyRosie I had a thought, watching the Live after reading your comment.
If we accept as (obviously) true that 'we've lost sight of what a healthy weight is' then it follows that we no longer recognise healthy-weight body shapes, with their varying visible skeletal structures and muscular definition.
The fashion industry was adapting to the new normal before society even began having the conversation. Hence the past decade or so of elastic and drawstrings, tiers and gathers, voluminous and easily adjustable clothing.
So it seems plausible that there is also a possibly subconscious effect, across society, including fashion designers and stylists, to smooth out variation and normalise everyone to a similar new silhouette. Layered, tiered, voluminous, to accommodate our overall larger/heavier/softer bodies.
Layers, volume, architectural, sculptural - these are clothes and stylings that hold a shape independent of the underlying body. Fabulous to give a defined silhouette to softness and roundness. However it also erases any hint of underlying skeletal or muscular structure, making even slim, toned models look bulky and dumpy. That's my momentary hypothesis, anyway :)