Miss, Why Can't We Study Happy Books?

This is something I've been asked many times, by different groups of students. It's true that we rarely do study books which are entirely happy (or sometimes, happy at all). Here's a representative list of some texts I've taught over the last few years, most for A Level, some for GCSE:

• Alexander Masters: Stuart, A Life Backwards (features homelessness, addiction, crime)
• Shakespeare: Othello, King Lear (great tragedy)
• Arthur Miller: Death of a Salesman, A View From the Bridge (modern tragedy)
• John Steinbeck: Of Mice and Men (isolation, dashed plans, inevitable death)
• Sylvia Plath: Ariel (mental illness, marital breakdown, suicide)
• Khaled Hosseini: The Kite Runner (rape, cowardice, betrayal)

See? But then, when did you ever see a 'happy' text on a reading list? Here are some of the things that usually feature in my answer:

• Conflict IS story. There's simply no narrative in 'everyone has what they want/need; everything's fine'. (The common answer to this is: But what about a happy ending? Couldn't we at least have that?)
• 'Serious' literature, which provokes thought, is often heavier in tone than more 'popular' literature. I can't explain why in any kind of satisfactory manner (which might tell you something about my views on the canon...), but happier writing is often taken less seriously.
• Have you ever tried writing a happy story, or poem, or song: it's hard! Or at least, hard to do without producing something cheesy, and cheese is not usually welcome on GCSE/A Level/uni reading lists.

Do you have any suggestions for other answers I could give? What would you say?