Although I don't listen to it frequently, I thought St. Anger was a brave experiment. So was Lulu. Moan all you want about Metallica, but they defy expectations and are not held ransom by their fanbase. That is why they are Metallica and not Armoured Saint.
Metallica is Metallica because Cliff Burton showed Het how to compose.
Kill 'Em All, written mostly before Cliff was in the band, was very much largely just a rehash of their NBWHM roots, musically and thematically, but
Ride the Lighting was neo-prog thrash with just enough raw rock sensibility to keep it from being too pretentious for millions of pissed off working class headbangers.
Master of Puppets cemented Metallica as thrash gods and they have been riding that wave ever since. Even devoid of bass,
...and Justice for All has Cliff's fingerprints all over it. Without those groundbreaking albums, no one would have given half a shit about the crap that was the "the Black Album" and given them a rabid fanbase to slowly alienate as they went from torn jeans to Gucci capri pants while playing grab-ass with pop-schlock production. I don't know whether to laugh or cry whenever I hear the semi-recent Avenged Sevenfold song on the radio that uses triggered drum samples from "the Black Album." IMO, the bravest thing they did post-Cliff was S&M, and even it was mostly bland. Now they're just a sad self-parody, I don't care how many millions they rake in. In 50 years, no one will care about
St. Anger, but "Harvester of Sorrow," "Welcome Home/Sanitarium," and "Creeping Death" will still be classics.