"Dead Poets' Society" and the Confusing Nature of Sadness

So, I just finished watching "Dead Poets' Society," as it happened to be on television. I still have not seen the very beginning, because when I walked in, the movie just happened to be at the part that Mrs. Allman reserved for the day in class that we watched it, just before the students are instructed to rip out the introductions of their poetry textbooks.
But in any case: Wow. Not only was the soundtrack amazing (two Beethoven pieces - can't go wrong with that!), but I was sucked into the character development to the extent that I had forgotten my mother's vague mention of the movie as we passed it one day in the movie store: "Now, there's a depressing movie." I suppose when she said it, I must have thought that the movie would end with the death (in old age) of Robin Williams' character, with all of the boys he had inspired gathered loyally around his deathbed. But no, I suppose that would have been far too cheerful. (Spoiler:) They take the boy's ringleader, the spirited character and martyred actor Neil, and combine his boyish impulsiveness with his father's obstinate close-mindedness to produce the grounds for the boy's suicide in the middle of the movie, just after he celebrates his success in the role of Puck for the school's production of "Midsummer Night's Dream."
Something about the way that entire scene is executed is devastating, even more so because of the setting (Neil's parents' house with pictures of himself as a little boy randomly placed) which accentuates his youth. His father has just announced that he will be placing Neil in military school, withdrawing him not only from his dreams of acting, but from his friends, and from the only legitimate role model in his life, Mr. Keating. After this sentence, Neil commences to make the speech he was advised to make by Mr. Keating (and which he should have made, as advised, before he actually performed in the play) about how acting is important to him, etc. But he is beaten into submission with a glare from his father and a dismissive, "You can just forget about acting." His mother then urges him to get some sleep, and he sits with a determined expression, at which point the audience becomes uneasy; one initially wonders, given the boys' innovation thus far, about how he plans to escape his house that night and make it back to the school and to his friends, and what his plans are from there on. However, this vague hopefulness is replaced with dread when Neil goes to stand before the open window with part of his costume from the night's play on, a peacefully determined and vacant expression on his face. Slowly, laboriously, he wanders downstairs to a desk, produces a small key (the audience furtively hopes, "Oh! This must be a car key, or something!" though they know this is false), and withdraws his father's gun from a desk drawer. When he is found by his parents, they fall into hysterics and the scene is complete.
What was so devastating about this climax in the movie, I guess, was probably the fact that the initial conflict was almost miniscule in comparison with other conflicts that the audience suspects will develop in a much greater magnitude than this mere disagreement with Neil's father over Neil's extracurricular activities. But, as noted above, it is this conflict which spirals out of control, while the others (the principal's suspicion of Mr. Keating, the discovery of the Dead Poets' Society, one of the other boy's pursuit of a girl, among others) are either resolved or affected directly by Neil's suicide. One example of the latter is how the principal takes the oppurtunity of Neil's death to lay the blame on Mr. Keating for "encouraging" the activities of the Dead Poets' Society along with Neil's acting dreams, hence the elimination of Mr. Keating's tenure as teacher by the end of the movie.
Of course, as one is already tearful for the remaining half of the movie (because of everyone's reaction to the death and because it is easy to hate the principal with a tearful passion), they decide to end the movie with one of those scenes which is meant to be a subtle, small, but yet beautiful triumph over the evil that seems to dominate (this evil being the principal, who has fired Mr. Keating and taken over his job temporarily as English teacher). As Mr. Keating is about to exit his classroom with his personal belongings, one of his faithful students stands on his desk and addresses him by the nickname he told them to use at the beginning of the semester: "Oh Captain, my Captain." Other students follow suit, saluting their former teacher, and ignoring the principal as he snaps at each of them to sit down. Mr. Keating beholds the reverent farewell that he is receiving, thanks the boys, and turns to depart. Then the credits roll.
So, my mother was right; the movie was depressing, and Robin Williams lived through the whole thing. Perhaps it was so depressing because the spiraling of the conflict was such an unexpected thing (that is, until just before Neil does the deed). But it was a well-done tragedy, much in the same way that Looking for Alaska was a well-done tragedy, and the book My Sister's Keeper. In each of these, the tragedy is a shock to the reader, and the "left-over" characters' reactions are very real and heart-wrenching.
So, as far as the nature of sadness goes, I just wanted to comment on a feeling I have shared with many others (from what I am told) that often, when tears seem to be called for in real life, it is hard to summon them, while when we immerse ourselves in tragic fiction, they come easily and at the right time. Why is this? Is it because when we read or watch fiction, we're not only crying for the tragedy, but also for the sheer art of it, for the poetic language or graceful movements - whereas, real life lacks that glamor and tragedy is often like a canvas stabbed through with a knife with nothing about the piece that can be glorified? Or does it have something to do with this quote of Dostoyevsky's from Notes from Underground: "Why, we don't even know what living means now, what it is, and what it is called? Leave us alone without books and we shall be lost and in confusion at once...We are oppressed at being men -- men with a real individual body and blood, we are ashamed of it, we think it a disgrace and try to contrive to be some sort of impossible generalised man." Is it that we use fiction as our means to know what we are to do with tragedy, how it should be dealt with, how one should go about their mourning - but that when we find ourselves in that potent reality, we are "oppressed" by our mortality, by our clinging to fiction as a way to cope with reality? Are we simply put into shock by how very real and beyond-control tragedy is? Are we so out of touch with what living "is, and what it is called" that we forget that we ourselves are characters in this huge plot woven by God which is impossible for the "generalised man" that we have created of ourselves to comprehend? Isn't it impossible for anyone to comprehend, for that matter? In any case, one can conclude that real tragedy is a jolt of faith in which one inches out on the branch of a tree to ponder the depths of a chasm which is said to have a soft landing place that cannot be seen from above, and the tip of the branch breaks off and falls within, followed by the fearful eyes of the living.
So, I will quit rambling now and retire.