Shatner has been much underrated as an actor since he became Jim Kirk.
This just brought to mind a piece of trivia regarding the film "The Intruder" starring Shatner and directed by Roger Corman (excerpt copy and pasted form IMDB
"Producer Roger Corman allegedly blamed star William Shatner's performance for the box-office failure of the movie, and the breaking of Corman's perfect track record of successes. Shatner jokingly suggested years later that the re-release title "I Hate Your Guts!" was probably aimed at him
Again my opinion, but having Hunter leave was a happy accident ...
Well, not so happy for Jeff Hunter considering his ultimate fate.