There were Lisp systems that were simpler than Unix, such as AutoLISP, Scheme, and later XLISP, but the ones that were competing with Unix in the 1970s were things like MACLISP, Zetalisp, and Interlisp, which were much more complex than Unix was at the time. I mean, Zetalisp had its own microcode, its own hypertext documentation, its own GUI, transparent persistence, and a WYSIWYG text editor, at a time when Unix had a couple of C compilers, man pages (its own typesetting system, to be fair), @ and # as the defaults to erase a line and a character, and ed as the standard text editor.

That's just the point, neither imperfection nor simplicity leads to viability, but taking less time and delivering something more appropriate does. You can make something simpler by stopping too soon or thinking too long; make something imperfect by not testing enough or sitting around adding bugs. ;)