Volume mostly. It's easier to do larger quantities of grain in an oven (or similar roaster) than it would be on the stovetop. Plus you get to set a target temperature (kind of). And with a slower toast, it's easier to halt at the desired roast.
Then too, the slower heat transfer may do something, compared to the faster roast of the stovetop process. (If coffee is any judge). Which has also made me wonder what fluid bed roasts would do. (Other than popping sorghum, which was a tasty snack when it finished.)
Don't know beerhound, this is the gluten free area, so I wouldn't know anything about barley.
Secondary: GF Czech Lager
Waiting to be kegged, Italian Primitivo
Kegged&Ready: GF Orange&Coriander, GF Honey Lager, GF chocolate ale, GF English ale, Island mist (zinfandel), Island mist (cbry malbec).
Bottled: Infected Mead, Dry Hard ciders, Accidental Sorghumwine, various unnamed.