Lighting Design is a specialized design genre; increasingly being taken seriously as an independent field. Outdoor lighting and Indoor lighting are the two broad categories of lighting.
In indoor lighting, awareness of the specific needs of the space and the user is critical to good lighting design. A judicious mix of primary and secondary lighting usually addresses most needs; however the styling and size and wattage are specifications that have to be factored in too. Of course many lighting fixtures and accessories are designed in a generic manner for interior designers/end-users to pick up what suits their scheme/desired ambience.
Besides one also sees trends where an extremely flamboyant lighting fixture is taken as the centre-point and the entire décor scheme is woven around it!