UNIX had a weak design. It won not because it was good, but because it ran on more computers. There are many other OSes of that time period that had superior designs.
The Lisp Machine had way better composition primitives than UNIX's pipes passing plain text around.
That is not the essence of worse is better. UNIX won over the others because it was simple and regular, and was built from components that could be reassembled into more complex things. Pipes were a big part of that.