From Joyce Carol Oates' intro* to a collection of H. P. Lovecraft stories:
Readers of genre fiction, unlike readers of what we presume to call "literary fiction," assume a tacit contract between themselves and the writer: they understand that they will be manipulated, but the question is how? and when? and with what skill? and to what purpose? However plot-ridden, fantastical or absurd, populated by whatever pseudo-characters, genre fiction is always resolved, while literary fiction makes no such promises; there is no contract between reader and writer for, in theory at least, each work of literary fiction is original, and, in essence, "about" its own language; anything can happen, or, upon occasion, nothing. Genre fiction is addictive, literary fiction, unfortunately, is not.
You could substitute music, movies, or web art for fiction in the above passage. The idea of a contract between producer and consumer and the artiste who violates the contract may have universal application.
*The original link for this quote was http://www.usfca.edu/fac-staff/southerr/lovecraft.html but it's broken now. Thanks, USFCA!
Update: through the magic power of the Internet the Library at USFCA sent me a working link. Much appreciation to Randy Souther.
Update, 2012: The link to the Lovecraft essay is dead again. In fact it appears that quote is no longer posted by USFCA. Have emailed to find out about this.
Another 2012 update: Haven't heard back from USFCA. The quote above also appears in a NY Review of Books essay by Oates. Am not sure how that differs from the book introduction I originally read and linked to - did Oates recycle the essay? It has other passages I recall from the intro, such as this one:
There is a melancholy, operatic grandeur in Lovecraft’s most passionate work, like “The Outsider” and “At the Mountains of Madness”; a curious elegiac poetry of unspeakable loss, of adolescent despair, and an existential loneliness so pervasive that it lingers in the reader’s memory, like a dream, long after the rudiments of Lovecraftian plot have faded.
Ah, here is another confirmation that the "genre fiction is addictive" paragraph occurred somewhere besides the NY Review - this is the book I was referring to:
On the same shelf I found the HarperCollins trade paperback of Tales of H. P. Lovecraft, selected and edited by Joyce Carol Oates. Though the text has shockingly narrow margins, I have to recommend it if for no other reason than Oates' introduction. Oates, like most rabid HPL fans, first read the author at age 13. (Does this mean that the Golden Age of HPL is 13?) 'Genre fiction is addictive,' she states in the intro. 'Literary fiction, unfortunately, is not.' Apparently it was HPL who addicted her.