Largely unknown at this time, or at least largely unframed as an actual problem, Hetfield's anger issues were not just creative devices for his music, just as his drinking wasn't just fun-times party stuff. They were real problems for him, and the issues would come to a head in 2001 when Hetfield drove out longtime bassist Jason Newsted
and interrupted recording of the St. Anger
album to enter rehab for his alcoholism. Hetfield's anger was a legitimate problem for him, which places "2 X 4" in a different light.
Any perceived (or real) "softening" of Metallica almost certainly ties into their physical maturity (they had all entered their 30s), and Hetfield may have been starting to look at his anger issues as faults to be worked on rather than things to glorify. None of that gentler sentiment is to be found on "2 X 4," however.