Several people have given the reason for clock changes as being to make more efficient use of the light. Surely, trying to ensure it's light when the majority of people get up isn't efficient.
Wouldn't it be far more efficient to centre the solar day on the hours that you could expect most people to be awake? Say, 9am - 8pm, because as far as I'm aware very few people get up after 9 or go to bed before 8. This would then make "midday" (in solar terms) 2 or 3pm rather than 12 noon.
I'm assuming the number of hours of daylight will expand around this centre point meaning we should get the maximum use out of the daylight hours. As it is it's light first thing in the morning (plenty of it at 7am when I got up), but dark by 5pm meaning all the lights go on for the whole of the evening when people get home from work.
This is never going to happen, but it does seem strange that we are so obsessed with it being light when we get up to the extent that we waste so much of the daylight.