It's anything but weird. I don't mean cotton cargos would be too dressy, but the pleated, stain-treated, pre-pressed heavyweight cargos from 5.11, yes, too dressy. I, or anyone else in the hot sub-tropical climate, would really stick out wearing those. Picture yourself at the beach. It's 95 degrees. But you don't wear a bathing suit, because you won't swim with your .380 in your pocket, but you want shorts that are comfy, breathable, and light. Not 5.11.
Now I don't know, it's been several years since I've shopped 5.11. Maybe they've come out with some softer cargos with prints, but that doesn't seem like the way they were going.