The Scorn About Memoir, Again

What is it about memoir that prompts many intelligent and learned people (who should know better) to poo-poo it? Yes, it's true that memoir has become somewhat of a literary trend lately and often for the wrong reasons (the proliferation of not-really-indispensable remembrances by the rich and famous is my pet-peeve example); but as a genre, memoir has a legitimate place in the pantheon of literature and should not be treated with the scorn that it is subjected to by many writers and readers alike.
I saw just one more example of this when I attended a public interview with Leslie Marmon-Silko , the wonderful Native American author. She has recently published a new book, The Turquoise Ledge, whose subtitle is "a memoir". It is, as her interviewer Molly Gloss pointed out, a memoir in the style of Annie Dillard's meditative essays on nature and the environment: Marmon-Silko lives on the edge of the Sonora desert in Arizona and, when not writing, loves to take long walk; the book is a collection of the thoughts inspired by and the incidents witnessed during, these walks—interspersed with personal recollections.
Molly Gloss is an author herself, of historical novels set in the American West and fantasy books; during the interview, she displayed a considerable scorn against memoir, implying that perhaps the new Marmon-Silko book should not have been labeled such (too good, or too serious to be a memoir?)
At one point she said that when one thinks of memoir, usually this conjures images of famous people writing about their achievements, or people with "dysfunctional f". The latter was uttered with a considerable smirk on Gloss' face—the implication being that only self-indulgent, self-centered people write memoir (and especially so when it is about "dysfunctional families"): the rest, the enlightened and "serious" writers, concentrate on either the more conventional end of non-fiction (ie. the politically-worthy, such as exposé journalism, or socially relevant essays); or, better still, they just write fiction.
Now, I am the greatest lover of fiction around; and I must confess that I read a great deal more fiction than I do non-fiction; and yet, apart from the occasional short story and poem, the thought of writing anything other than non-fiction, and then again other than personal non-fiction stories, has never occurred to me.
Why? Because, as an old and old-fashioned feminist, I believe in that little dictum, "the personal is political"; and I believe that, by writing memoir, we can both satisfy our "reality hunger" (with apologies to David Shields —someone who certainly doesn't have a narrow idea of what non-fiction is) and communicate something that will be socially and culturally relevant and of interest to readers other than our family or friends. In fact, let's explode once and for all the myth that the only people who will be interested in reading our memoir are our next of kin or our closest friends: oftentimes, these are in fact the people who end up being our worst critics and least enthusiastic readers, because of the personal investment they too have in our life story—and the fact that their perception of the "facts", the "truth" may not exactly coincide with ours. Many memoir writers talk about this problem—see for instance Louise DeSalvo and Mark Doty .
As a rebuttal to all those who scorn memoir: all good writers, even when they are writing about themselves, are capable of separating their real life from their real life as it exists on the page, where it ceases to belong to them alone and becomes an artistic product, becomes public domain.
I had just one of those "dysfunctional families", but the reason I came to believe I ought to write about my mother's madness and terrible life was not therapy; I have never confused art with therapy: when I want therapy I go to the therapist, when I want to write, I go to my desk. It was instead because I realized that there was a story there, potentially interesting to other women (and men, too); a story about madness as it related to gender, as it related to a specific culture. And that I could tell that story in a voice that was both poetic and critical.
Yes, it is possible to write memoir that is utterly solipsistic and narcissistic, and indeed there are many books like that out there; but there are also many crappy works of fiction, so would this latter fact be enough to disqualify the entire genre of fiction? Should we look at books as entities within a labeled box, as part of a genre—or should we look at books as we ought to look at human beings: each one unique, each one the product of a particular culture, historical moment, the product of a creative mind inflamed with a timeless yearning: the desire to tell a story?