Your metalhead friend was correct. I personally think that that "Metallica" died with Cliff Burton. No hate to Jason Newstead, but Cliff was the one in the band with musical integrity.
Justice was really important to me. It was the first album I ever loved at the age of eight. It introduced me to the rest of their catalogue and, of course, fell in love with Burton and bass guitar. Too bad they did Newstead dirty on that album. But Justice sparked some political consciousness in me. And musically, I think they stretched as far as they could. With Burton, it would have been farther, but still farther than those three had stretched before. The same is not true for the black album.
I agree completely. There are versions of Justice that can be found online where the bass is mixed back in, and I highly recommend them. Newstead put in work on that album.
When the black album came out, Metallic instantly went from legit thrash band to top 40 hard rock and was on the radio all day everyday... and somehow they still are and it's baffling.