Well, bash specifically didn't; AUI, it's still very much a GNU (hence mainly Linux & Cygwin) thing, with other environments generally favoring some Korn variant. But as for the general Bourne vs. C, I believe it's just because of the general braindamage (four serious scripting purposes) of csh. See csh programming considered harmful. In light of that, and the advanced bourne shells all incorporating csh improvements anyhow, I suppose it would be sane to let go of the cshes for interactive use, too. But since I've been using tcsh since last millenium, I'm sticking with it.