Lighting in restaurants has recently become recognized as one of the basic ambience factors that make an investment successful or not. Regardless of the quality of the food, if people do not feel comfortable in the establishment, it is very unlikely to survive long. The cost of good lighting, compared to bad, is trivial compared to costs associated with ownership or rental of the space, and ignoring the value of intelligent optical and psychophysical design would be like economizing on the salt and pepper. I believe, although I do not have proof, that office lighting could be markedly improved for a very small expenditure per office, especially if the problem is addressed somewhere in a coherent, organized and well-financed way. The value to be gained here is that as employees would have lower stress and greater job satisfaction, one should find that turnover and illness rates decrease and productivity is enhanced.
Art is also much more easily seen and enjoyed when the lighting has been properly arranged.
Indeed, for some times of art, such as holography, it is not even possible to see the image unless the lighting is appropriately controlled. This area has been the forte of my brother, Dan. Until he gets around to his own page, there's a Dan Kainen page here with some information on his New York lighting studio and workshop in SoHo.