Depends I think :) If you're counting something to be worn in winds and stuff, then actually there has to be a strong argument for using very light coated fabrics.
Totally windproof and rather more water resistant of course. Only ~40g extra on a PHD jacket from MX to Drishell so the weight difference isn't extreme and you even get some static warmth while you're at it.
+2 degrees on the EN values for RABs sleeping bags for endurance vs quantum for instance. Suspect also a non trivial portion of why the anti freeze tested quite so warm in the recent group test.
Of course thats a fixed amount of extra warmth so sometimes the very lightest fabric lets you add enough extra down to be worth using. Or you'll be mostly sleeping in it/wearing a windshirt over the top etc etc.