Not really the "fault" of UNIX. The Lisp workstations would have been just as unpopular without it. They were insanely expensive and the idea of a workstation was ahead of its time, not to mention the other "unneeded" extras like GUIs, a mouse, and the photo editing and 3D modelling suites. It was plainly uneconomical.
UNIX was only cheap because AT&T was forbidden to profit from it, had it not been the case, it would have been a proprietary closed source OS, exactly at similar price points.
The proof being the graphical UNIX workstations from Cray, SGI, Sun, NeXT that came later into the market.