Bollocks! Neil Gaiman didn't pitch The Sandman as part of the Wild Cards books, did he?! Hell, I have Absolute Editions of the entire comics series, and they had a pitch document.
...Okay, I checked Wikipedia (specifically the page for Wild Cards), and apparently, Gaiman did pitch something similar to Martin. I was under the impression, though, that Gaiman originally intended The Sandman to be as a sort of revival of the 70s comic series, only, he wasn't allowed to do that by DC. They wanted him to develop a new character with the same name.
I actually didn't mind the Wild Cards books. I mean, you have Watchmen and The Boys on one end of the scale, and My Hero Academia on the other, and Wild Cards sorta sits between them in terms of darkness...