We all know how important it is to have sufficient lightning, not only inside out house, but also outside. For me it gives a sense of security, specially at night. Aside from that, I believe that having the proper light can also deter some of the burglars that might be planning on doing their bad acts, since the light can let everyone know and see what's happening.
Of course, it will greatly help if your light's design is also meant for the situation, like if it's appropriate for the outdoors, then you should look for Outdoor Light Fixtures. Similarly, lights to be used inside the house, like Bathroom Lighting, or Ceiling Lights are important, too. Lights which will be used for different locations are designed differently since they will also be subjected to different environments. It is then advisable to buy and use the light where they are intended to be used.
As for me, whatever their use, I just know that they are important. They have been there for as long as I can remember and I know that they are here to stay. If you get one with great designs, than it's much better, but if not, then as long as they serve their purpose then it's fine with me. :)