Re: http://www.theatlantic.com/education/archive/2013/10/the-folly-of-the-sat-writing-section/280510/
On the question of “who can write a decent essay in 25 minutes?”, perhaps students should join forums and post frequently. 
The writing section is the descendent of an English composition achievement / SAT-II test. Some universities, like the UCs and Harvard, noted that the correlation between the score on that test and college performance was stronger than for SAT-I scores. However, after that test became part of the SAT reasoning, test prep companies started emphasizing how to game the writing section and its grading, probably reducing the value of the writing section as a predictor of college performance.
Many other schools that never used the English composition achievement / SAT-II test just continued to use the other two sections of the SAT reasoning test in order to stay consistent with former practice.