Meanwhile the creator of R wants to return to a Lisp-based statistics environment:
I can access the paper because my school subscribes. If anyone wants to read it, figure out how to email me and I'll send a copy.
While searching, I did find a brief email from Ihaka talking about the jump to Lisp: https://stat.ethz.ch/pipermail/r-devel/2008-May/049501.html