[wavemachine]

I think another issue is that bright light will cause the pupils of the models eyes to dilate more and make less flatering portraits, as Kezpock pointed out they do get hot and make models more uncomfortable but for me it isn't just the heat, being in an environment with softer lighting will naturally cause a more relaxed atmosphere for the model to work in.

Direct light for still life however is a different kettle of fish but even then you still probably would want to difues the light in most situations.