grimwerk: Daylight Saving is applied in the summer. That is, in the winter, the clock is normal. In the summer, the sun rises early, before most people begin their day. Still, most of us go to bed after dark. So we shift the clock forward, to take advantage of that early sunlight. And there are a whole pile of advantages to do so.
People could simply go to work one hour (or 4 hours, or whatever) earlier, if they think it gives them some great benefits. All the year around, not only in the summer. Thailand is one of those countries not using daylight saving, and they seem to be doing great without it. Rice workers still go to work as soon as the sun rises, they don't have to be tricked to do so by shifting the clocks twice a year. Same goes to e.g. India, I think.
The whole Daylight Saving is made even more stupid by the fact that different parts of the world shift it at different days.
BTW, does Australia, New Zealand etc. shift the clocks in the opposite direction, as our summer is their winter?