I feel like that Billy and Co always stayed true to their roots and what they did best, even if they experimented a bit, charts and sales be damned.
IMO everything after Master of Puppets (Justice was just 'good' and sounded like shit) was mediocre at best. And other than Hammett, musicianship is below average. See Ulrich, Lars.
I think a lot of their early sound was led by their early Dave Mustaine influences, and when they went their own way a little bit... well... you know the rest better than anyone. They singlehandedly wrecked the US scene at the time.
I also add this Chuck Billy vs James (YEAH!) Hetfield isnt even a contest.