There’s slim jackets and pants, and then there’s the stretchy stuff, which I never see in the PNW, but saw a lot of at Aspen. Sometimes zebra stripes or shiny gold or silver. Not sure if that’s more of a Euro thing, but it definitely is more about fashion than function. Probably not about aerodynamics, as the people wearing them often aren’t skiing much at all, and when in motion not going fast enough for aerodynamics to matter.
OTOH, a lot of the baggy look is the influence of snowboarders and parkrats. I have a Burton AK jacket that fits like it’s two sizes too big (well it actually is two sizes too big, but even if correctly sized for me is still pretty loose) and FlyLow shell pants that are a way looser fit than my Patagonias. You often see hoodies worn rather than a shell, just a very casual style.
But try on a Spyder, way more form fitting (for better or for worse). Most brands know who their target market is/are.