I can't say I see it, necessarily...but I also never saw him as Cobra Commander, and for all G.I. Joe's flaws, G-L Joe was not one.
I think we're naturally inclined to assume that Morpheus ought to be English - he's pale, intellectual and mopey, after all - but there's no reason a guy as versatile as JGL couldn't pull it off. I just feel sorry for whoever gets cast as Death - invariably a million idiots will claim she's not hot enough, or white enough, or whatever (hint: NOBODY's white enough).
I'd like to see him write the thing as well, because frankly the thing that makes me cringe the most about this whole project is the idea of David Goyer adapting the work of Neil Gaiman, which strikes me as the equivalent of getting of getting Stephenie Meyer to write a sequel to Romeo and Juliet.
This probably won't get made anyway - Sandman movies are always talked about a lot before not happening. But if not JGL, who?