I feel that in the early years of Metallica James was quite selfish of the guitar playing. Note that 'Enter Sandman' is sometimes referred to as the first riff Kirk wrote, so whao wrote all the Riffs from the first four albums? James of course, and Cliff may have had some input too.
Also note that in the 'Some Kind of Monster' film when James says that when Lars and Bob etc are discussing things in the studio after he has left, he says that everything for him is "an uphill struggle", and Kirk replies with: "That's what it's been like for me for the last 15 years."
So, do you all think that James and Lars were selfish and ignored Kirk for the first four albums? Another way of looking at it is that when Kirk was allowed some of this musical input, Metallica's 'decline' began and they became 'radio-friendly'.