It's only really sad that such a great prose stylist was ignored for so long. I'm glad that British newspapers commemorated his death (though perhaps typically, the Telegraph refer to him only as a "seventies writer"; his most popular and famous books were written through the 60s, 70s and 80s), but they only seem to have managed it because a heck of a lot of more famous, but inferior, writers (GRRM, Moorcock, Le Guin, Gaiman) have cited him as influences and expressed their sadness at his passing. I don't think I know more than, say, four or five people who've even heard of the man. Like Harrison and Wolfe, he's somehow missed out on the mainstream success which fantasy/SF is beginning to achieve.
I think there are various obvious reasons for this. Unlike writers such as GRRM, William Gibson, China Mieville, or Paolo Bacigalupi, there is nothing 'cool' about Vance's writing. (I don't mean to use the word 'cool' disparagingly: I like three out of those four writers very much.) His favourite author was PG Wodehouse and there is something old-fashioned about his writing: he seemed to eschew the modern and contemporary in favour of a very recherche, arch, and almost polite style - as if the modernist revolution never affected him. And he was damned by the pulpiness of his titles, covers and publishers, which, unlike the writing, feel very much of their time - people don't write books with titles like The Languages of Pao any more.
But I think there is another reason, which is simply that Vance is a very cold and detached writer, who doesn't make concessions to the reader. That's not to say his writing is difficult to get into; it's just that it's difficult to get emotionally involved in. This is because Vance is first and foremost an amoral author. Not amoral in the pejorative sense, nor in the juvenile everybody-gets-raped sense which sometimes lets down A Song of Ice and Fire. Amoral in the sense that, as a narrator, he never engages in the making of judgements. Even when he is describing horrific behaviour (there is a particularly memorable scene in the first Lyonesse book in which a woman gets her tongue removed) he never allows himself to indulge in telling the reader how to feel about it: his tone and voice always remain detached, neutral and objective. He is always meticulous about allowing the reader to make up his own mind about the morality of what he is reading. (And it is a mark of his skill that he gets you to fall in love with Cugel without ever trying to represent him as sympathetic.)
This is something that it is difficult to love, I feel. If you get Vance, you get him, but if you don't, you probably wonder what the fuss is about. His great strength is something that militates against mass popularity.
I don't mind this, however; if you do get Vance, it's probably a sign you are simply a superior human being, and you are a member of a very lucky set of people. As I wrote a few years back:
There are moments reading Vance where he is simply so brilliant, so much of a virtuoso, that you can hardly stand it. My particular favourite episode in all of the work of his that I've read is the chapter called ["The Inn of Blue Lamps"], which comes near the start of Cugel's Saga. The depiction of gradual descent into drunkenness of the characters involved, the understated humour, the slightly sardonic detached tone in which it is written, and the joyous unfurling of the tightly-wrought and carefully constructed plot (the creation of which you haven't even noticed because it has been done with such aplomb) - it's enough to make you remember all over again just why literature is enjoyable and important.
I'm off to re-read that chapter now with a glass of brandy - here's to you, Jack.