In the UK, we have a man called William Willett to blame for the endless (well, twice a year) fiddling of our clocks, as it was Willett who convinced some MPs in the early 1900s that it might be a good idea to shift the day about to make better use of the seasonal changes in day length.
Willett originally proposed a complex system of gradual changes to the clocks, shifting things about by 20 minutes in spring and autumn, with Willett explaining the benefits as:
"If we will reduce the length of four Sundays by 20 minutes, a loss of which practically no one would be conscious, we shall have 8o minutes more daylight after 6 p.m. every day during May, June, July and August, and an avenge of 45 minutes more every day during April and September."
And as is often the case, it was a bloody great war that brought this technological change into place. The UK's clocks were first changed away from GMT by one hour in May of 1916, as part of the war effort and to maximise daylight hours in the evening when the nation was busying itself building bombs and ships.
The crude basis of the idea is simply to get people up earlier in the summertime, maximising productivity during daylight hours and, hopefully, saving some energy used up by lighting in the proces. So, at the end of October, we're not really turning them back. We're reverting to the norm of GMT.