I really do not know. I suppose one could argue that biological systems seem to optimize themselves to take maximum advantage of the niche they have. In this case the niche is being able to take the best advantage of the available daytime light, just as 'growing long necks' was an adaptation to eating leaves off tree tops. Also, I think it is true that photons in the optical range of wavelengths are at energies that are compatible with the widest range of biochemical reactions involving carbon compounds, and the flux of these photons from the Sun is maximal in the visual spectrum at the surface of the earth. I do not believe that the atmospheric window has exactly the same detailed transmission as the responsivity of our retinal photoreceptors, but I think the bandwidth from blue to red is very similar. Perhaps some biochemist 'out there' has more to say about this?