Millions of fans were thrilled to see Slash and Duff McKagan back in the lineup for this year's Guns N' Roses tour, but it's still unclear if or when the reunion will produce any new music — and from Metallica guitarist Kirk Hammett's point of view, once a band stops creating, they've lost something truly crucial.

The subject came up during a recent Los Angeles Times profile on Metallica, in which the band's current activity — including their soon-to-be-released new album, Hardwired... to Self-Destruct — is held up in stark contrast to the wave of other acts from their generation who have retired, passed away, or are touring behind older material. That latter group currently includes Guns N' Roses, which Hammett thinks is a bummer.

"Unfortunately," he told the Times, "they’ve turned into somewhat of a nostalgia act, which to me is kind of sad."

"I don’t want to think we’re trying to stay young by writing new stuff, but it makes us feel relevant," added frontman James Hetfield. "It makes us feel like we’re still progressing."

Of course, veteran acts have turned away from recording new material in recent years for any number of reasons, including dwindling overall sales across the record industry and the always difficult prospect of living up to one's own previous work. That's a struggle Metallica are intimately familiar with, but they insist owning their own label — and the challenges of figuring out how to best take advantage of the new digital landscape — have energized them during their Hardwired era.

"I mean, God," added Hetfield. "If you love what you do, why stop doing it?"

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