Some authors are immediately accepted after a certain work of theirs; the others become famous only after death. Does it mean that all the rest don’t deserve anything more than fleeting attention? Not exactly. There is always a number of writers that didn’t manage to write right books at the right time and ended up in obscurity, rather than becoming famous or at least well-known. The examples of such writing appear both in serious and light literatures: it has little to do with the overall people’s taste.
For example, there is Charles Williams, the author of seven novels that no one quite managed to put anywhere because of their really strange nature. While featuring strictly entertaining qualities and plotlines involving the quests for the Holy Grail and the Major Arcana no serious writer can ever write about, they are flooded with interminable reflections, dialogues on deeply philosophical topics, obscure symbolism and other features that would only confuse and bore an average reader.
Or, speaking about entertaining literature, there is Tim Powers, an author of several novels that are always quite difficult to put anywhere – not exactly fantasy, but not science fiction either. They are quite different from the mainstream, but still belong to the genre of light literature, and suffer because if it, for average readers want to deal with something familiar, and intellectuals don’t want to deal with light reading.
And, as I suppose, an author becomes underestimated precisely because of this – because his works do not fit into the image of the kind of literature he works in, no matter whether it is serious or not. Even among authors the readers don’t like the eccentrics.