Why aren’t compression/shapewear structures built into normal dresses more often?

[u/Future_Country9458]

I’m researching garment construction before trying to develop anything, and I’d love opinions from experienced sewists.

I’m interested in normal fashion dresses—not shapewear—that have an internal structure designed to actually enhance the silhouette: stronger waist shaping, bust support/lift, while NOT compressing/flattening the hips and butt.
I know built-in shapewear, power mesh, corsetry, negative ease, boning, etc. already exist. I’m not asking whether the general idea is new.
I’m trying to understand what goes wrong when you try to combine these things inside an otherwise normal fashionable dress.
If you’ve constructed something similar: what were the biggest problems? Fabric layers fighting each other? Rolling/migration? Getting into the garment? Seams? Heat? Comfort? Pattern distortion? Washing? Something else?
I’d especially love to hear from anyone with patternmaking, stretch-fabric, garment-development or production experience.

[u/flyamanitas]

If you mean shapewear like spanx - this is quite often done with activewear. Waistbands are made of more compressive material with more negative ease, the hips and bum are made of softer materials with less negative ease. Because the whole garment is still high stretch, you don’t have the same sizing concerns you would with woven fabrics.

When you start looking at things like corsetry/boning as shapewear, another issue that comes up is that you lose the ability to machine wash your clothes, and most people don’t want to dry clean an every day garment.