What a lively discussion :-)

1. Principle of least surprise
BSD for some time, and NetBSD (forever) have shipped with a root shell of
csh. If we're going to change defaults we should have a good reason.

2. Utilitarianism
I don't know anyone who uses /bin/sh as their primary shell. I _do_ know
some people who use /bin/csh as their primary shell. Those who prefer the
sh stylings, (or who dispise the csh's linguistic limitations) are likely
to install bash, ksh, etc... (etc is NOT a shell! ;-)
For the basic user, csh provides more interactive nicities than sh. IMO.

3. The single user /bin/sh argument
/bin/sh is the default shell in single user mode (or, the suggested
shell at least) likely because singleuser mode is meant for performing
low-level system maintainence. The system is running in a limited
fashion, and /bin/sh makes very few assumptions about what may be available.

-- 
David Maxwell, david@vex.net|david@maxwell.net --> Mastery of UNIX, like
mastery of language, offers real freedom. The price of freedom is always dear,
but there's no substitute. Personally, I'd rather pay for my freedom than live
in a bitmapped, pop-up-happy dungeon like NT. - Thomas Scoville