But here's the thing. You ARE, of course, correct that your opinion is your opinion, and when it comes to "what you like" that's unassailable. I won't ever question that, except maybe to offer a counter, just for discussion purposes. For me, though, the discussion changes when you say "thrash bands... shouldn't evolve so far away from it". That SOUNDS like an opinion, but it's really not. You're basically telling Metallica what's an appropriate level of development, personal growth, and exploration. We can comment as to whether we like it or not, but only Hetfield, Ulrich, Hammett, and Trujillo (well, Newsted at the time) can tell you what's appropriate. I wouldn't be at all surprised if there wasn't extra-musical reasons for their evolution (meaning, maybe Hetfield, in particular, couldn't emotionally, physically or psychologically have continued down that path) and so at that point, "opinion", while technically, I suppose, correct, becomes something more than that and doesn't really get to be "protected" by an "IMO" at the end.