Well, it's a pretty good fantasy comic for adults. It's not the only one, nor the first, but it's pretty good. And fans tend to be zealous of those. For many of us, it holds a special place in our comics-reading education, and so we would not wish to see it demeaned but yet another low quality adaptation that completely misses the point or dumbs everything down.

Thankfully, it doesn't seem to be the case with this adaptation of The Sandman :)

edit: this is what Gaiman has to say about The Sandman's cultural significance:

"And after 30 years, “Sandman,” at this point, is probably the single best-selling series of graphic novels ever published in the U.S."