They had an interesting reason to use/discard Lisp:
"The real reason we stuck with the LISP-ish syntax is that we didn't want to be fiddling with the parser while designing the language, and (to a lesser degree) because we didn't want to encourage programmers until we thought the language was ready. We are now preparing a more sensible surface syntax, whereupon we will receive rotten egg and tomato complaints from the LISP community. You can't please everyone. Using the LISP syntax for so long let us focus on what was really important."