While reading up on various methods of rooting cuttings, I note that many folks say to put the cuttings in a warm, dark place.  I've seen explanations about the warmer temperatures and humidity being key factors in how quickly cuttings will root...but how important is the "darkness" component?  All other things being equal, would a baggie with a cutting in a dark place root significantly before a baggie with a cutting in a bright place?

Darkness is not needed. However, you want to keep them out of direct sunlight or away from heat sources that can cause them to be cooked or to dry out. Direct sunlight is very powerful and can overheat them very quickly.

However, because the roots and shoots will develop from the energy stored in the cuttings, light is not essential, either.

I had cuttings root in 7 days in a natural lit room.  I never kept them in darkness unless it was night time.