In real life I can see the sun and most importantly it shows up in reflections. Right now if I want to reflect the sun with yafaray I have to use a sunsky or DTsunsky. Neither of these offer the very intense focused .5 degrees of light in reflection that should show up even with low levels of reflevtion or high exponent glossy materials. Faking this with area lights or point lights is cumbersome and unrealistic.
I am not familiar with the yafaray code in specific to know how difficult this is to implement, having only a brief understanding of how ray tracers work it would go something like, rays that end in the sky at an angle equal to the sun's direction +- .5*sun's angle receive the color of the sun times a high factor. Blackbody coloring and brightness (even through a cheap conversion using Wien's Law) would be nice but is entirely unnecessary.