At the center of this question is a problem of definition, namely what counts as literature. In order to say "x is literature" or "y is not literature," there must be some rigorous way of delimiting "literature" from "not literature." Also, the question presumes that there is some...
At the center of this question is a problem of definition, namely what counts as literature. In order to say "x is literature" or "y is not literature," there must be some rigorous way of delimiting "literature" from "not literature." Also, the question presumes that there is some way to make a clear demarcation between "serious" and "genre" fiction. Unfortunately, there is no non-circular way to engage in such definitions.
Let us take a specific case. Is Jane Austen's Pride and Prejudice "genre fiction" or serious literature? What about a "Regency Romance" from Harlequin? In both cases, we may have a plot structure that revolves around girls from relatively ordinary families overcoming several obstacles (including usually a smiling seductive villain) to marry some of the richest men in England. Similarly, Jane Eyre has just as silly and improbable a plot as any "gothic" romance (such as Radcliffe's Mysteries of Udolpho). A poor, physically unattractive young governess and a rich man married to an insane wife he keeps in his attic fall in love, but then young woman runs away, discovers she is an heiress, hears the rich man calling her telepathically after the insane wife has died in a house fire, and they marry and live happily ever after.
What the examples above show is that we don't really have grounds on which to distinguish "serious" from "genre" fiction by any objective criteria such as plot structure or character types. Many different works that are widely taught in schools, such as Mary Shelley's Frankenstein, George Orwell's 1984 and Animal Farm, Aldous Huxley's Brave New World, and Margaret Atwood's Handmaid's Tale similarly fit under the conventions that define "science fiction," another type of genre fiction.
Whether readers read works to re-examine long held assumptions or simply to enjoy the story depends on the reader, not the book, and thus reader response does not really create a rigorous distinction between "serious" and "popular" fiction. Even further complicating this issue is that some works we now study and call "serious fiction" were popular, published as serials in magazines (Dickens, for example, in style, plot structure, and publication history does not really differ from other "sensation novelists").
These sorts of issues are what have led most scholars over the past 30 years or so to conclude that the very distinction between "popular" or "genre" fiction and "literary" or "serious" fiction is an artificial one and to abandon the distinction as simply lacking intellectual rigor.
Thus I would say that there are some books written in clearly recognizable genres, such as Pride and Prejudice (romance), Jane Eyre (gothic), Lady Audley's Secret (sensation novel), Island of Dr. Moreau (science fiction), or 1984 (science fiction) which are well worth reading and studying. Many highly skilled authors prefer to work within the boundaries of genres such as science fiction or romance. That less-skilled writers also work in those genres is no reason to dismiss a genre as a whole. Each book should be read and judged on its own merits.