The "do I go to film school or not?" question has been debated to death here on IndieTalk and myriad other forums, and the answers are as varied as the people who attempt to answer the question.
As to the purpose of film school...
Most professions are very technical in nature and require very specific knowledge - law, medicine, finance, engineering, the sciences, etc. The "arts" require just as much technical knowledge as any other. Knowledge is objective; it can be quantified, graded, enumerated, etc. as it is very specific. The problem with the Arts - writing, painting, dance, music, photography, film - is that the application of all the objective knowledge is applied in an extremely subjective way. So your failure or success will depend upon how well you apply your accumulated objective knowledge in a subjective format.
The problem with film schools is not that they focus on the technical aspects of filmmaking, it is that a very large percentage of the students come out believing that technical knowledge is all that is required to be a filmmaker, and tend to turn their noses up at those who do not get a formal cinematic education. And the converse is also true; those who have learned on their own look askance at their formally educated brethren who "wasted all that money and have nothing to show for it."
Everyone has to adapt their learning to their own situation. Some folks are very comfortable in a formal educational atmosphere. Others are much happier learning by doing or in a more casual learning environment. My point of view, because that has been what has worked well for me, is "learning what I need to learn"; that is to learn by doing, hit a knowledge or technical roadblock, and then do some intensive research to fill the gap. That may be reading a book, or taking a seminar, or a short intensive course. Sometimes I even get lucky enough to get advice or a consult with someone I admire.
You will get out of your education what you put into it. You get out of your career what you put into it.
But no matter what you do the creative inspiration comes from within the artist, and no amount of schooling or otherwise acquired technical skills can substitute for talent.