What is your benchmark for a lightweight 20 degree bag?
The Montbell UL SS Downhugger #1, a 15 degree bag by most accounts, comes in at 36 ounces and most would consider this to be very light. The #2, a 25 degree bag, still comes in at 1 lb. 15 oz. The Western Mountaineering Sycamore, a 25 degree bag, comes in right at 2 lbs. I use these as benchmarks because they, like the Golite bag, are wider for broad-shouldered or large folks.
The WM Ultralite, another 20 degree bag, for example, is about 8 ounces lighter but much more restrictive. Therefore, a comparison to this bag is not as telling or accurate as it would be to the others mentioned above.
IMO, I don't see how 34 ounces is not lightweight for a 20 degree bag of this size. If you're comparing quilts or something to this bag, then you are probably right. But, you're also comparing apples to oranges.