Unix was meant not so much an anti-Multics as a mini-Multics. Unix had to run on a PDP-7, after all, and then a PDP-11, vs. a mainframe that could have a whole megabyte of memory. In other words, by today's standards, big fat Multics was small.
But it had features still missed. Security was central. It had rings of protection, enforced by the hardware (unlike Unix, it was not meant to be portable). The zillions of Unix exploits that plague today's descendants would not be likely to work in Multics. Frankly reviving it for modern hardware might be a useful exercise in security.