I'd just like to point out that the same could be said for the chiseled abs and pecks of every human male we've seen. People didn't work out in the middle ages, you don't develop that sort of muscle from normal day to day activities.
This is also true, but you also wouldn't have the ladies looking the way they do either. They wouldn't be the super-busty sort; if they were slim they'd be slim all over. You forget that the ladies are not only very toned in the Dragon Age series, but they also seem quite well endowed. Usually you don't see those two things together unless someone's had surgery to augment her breasts. Yes, it's possible--just not very common.
I suspect there would be at least some who'd be "chiseled," but they would mostly be the athletes of the world--people who tourneyed frequently, foot couriers, etc. People who had enough to eat but had to work to get it, basically. Most people would be on the slim side; the more successful folks would be heavier and softer because, well, if you were noble or rich enough, you basically wouldn't be doing any of your own work. (There were even laws against it for nobility.)
The chiseled, slim, sexy bodies are basically part of the fantasy of it--though sometimes there's a different kind of fantasy going on in some of the designs.
But the point is, hardly anyone has that same build as a qunari male, and perhaps the females should be bulked up to match if that's a defining feature of their race. I really doubt that the women would be so slender and delicate in comparison, especially since we know that many of them do a lot of hard physical labor.