The difference IMO, is that Metallica were innovators of an entirely new genre of metal. They were the trend setters.
With TBA and beyond, it began to feel more like they were taking their “sound” and following those who had come before them, or as with the Loads, their contemporaries.
They went from trend setters to trend followers.
I don't think it's necessary to accuse them of being trend followers.
The kind of music they were interested in making changed. No more, no less. Not unlike Opeth over the last several years.
I agree with JD. But, I also feel like it can be a little bit of both. They DID follow trends. And did starting with TBA, and then onto Load. But I think it's also true that they wanted to go someplace else with their music.
So, all of that.
As artists, Metallica felt they had nowhere else to go or explore in the thrash metal area after AJFA. They couldn't play faster, or more technical than that album. They've said that numerous times. Instead, they went elsewhere. But by doing so, they also started following trends of what others were doing, and naturally exploring other areas of their music abilities.
I think that's pretty clear. I think after the Loads, they tried their own thing with St. Anger, it bombed, and then they went back to try and replicate the more thrash/prog-thrash side of themselves with DM (which to my ears, is the most contrived record I've ever heard), and then since then, they've sort of settled into a groove with HW, and now 72 Seasons of just writing songs inspired by what they love, almost old school like, but without the need to be the heaviest band on the planet.
It suits them. But to THIS fan's ears, it sounds like old guys who are past their prime, and just playing tunes. And there's nothing wrong with that. It doesn't inspire *me* as a listener, but I am sure, as has been proven here, they still sound great to others. And that's cool. But to me, Metallica has become what Tesla sounds like, sadly, today. Music that sounds like a bunch of old dudes just jamming on stuff they like, but lacking fire. For some that works. For this old school Metallica fan, it doesn't. And that's okay. Obviously, I'm in the minority, and I'm okay with that.