Corporate offices started the trend. Government and public sector offices caught up with it. And now even educational institutions and homes are following the pointless practice. I call it the 'cocooned-indoor-syndrome'.
By constructing closed and cocooned work-places - where you don't have a sense of day or night - the trend-setters i.e. the employers probably expected you to work away without concerns of passage of time. But for heaven's sake, I hope they realized that most of us have at least five different ways - own watch, cell phone, corner of the desktop, co-worker's watch and hunger - of finding out what the time is. Once the trend is set, you always have hordes of followers who actually don't know why they're doing it but will still do it convincing themselves with excuses like 'higher standard of living', 'progress', and 'development'.
When you have so much of natural light available during the day, why does everyone keep themselves locked inside dark dungeons that need (read waste) thousands of valuable watts trying to light up the work-space?
But yes, lighting takes up only peanuts of power when you compare it with the most gluttonous of all electrical loads - the air conditioner. So the idea is you make your work-space air-tight and then install air-conditioners to heat the surroundings of the building (well actually, may be to cool the indoors so that people inside can use suits, jackets and shawls) well enough so that people coming from outside crave even more for the air-conditioned interiors. In most cases, ceiling fans are more than enough. How about planting lots of trees around the building and opening all the windows? Why not take care of cooling and ventilation in a much more economically and ecologically saner way?
The cynics say "Can you bear 40 degree Celsius?". I answer "It certainly is difficult. But, if I don't bear it now and give in to AC's, I might have to bear 50 degree Celsius within a decade!". If you feel for the cause, do join the 'khidki kholo andolan' (losely translates to 'the open-your-windows movement').
[Disclaimer: Most of the above arguments hold for hot countries like India and not for cold countries]
