I doubt anyone would ever suggest that the fact that a coach cusses is intrinsically a bad thing.
However, there is a certain kind of coach--maybe some of us played for guys like this?--who adopt a blustering, tough-guy attitude in lieu of actual coaching skills: scheme, in-game adjustments, player motivation, etc. For many people, cussing is a hyper-aggressive way of papering over deficiencies.
Is that true of Williams? I dunno. I don't watch these shows.
I just think that the guy is a vastly over-rated DC who did a piss poor job of recognizing the strengths of a talented group and maximizing their effectiveness.
I am always amazed at how many Ram fans speak admiringly of his work with our lads, work which, IMO, wasted the considerable talents of a fine defensive roster and led it to continuously under-achieve. But, whaddo I know?