Their newer style appeals to a much broader audience than metal. I recall a Hetfield quote from one of those VH1 Behind the Music docos: "People say we sold out...yeah we sold out, we sold out every venue we played."
They did not sell out Turner Field in Atlanta for their 2003 show. I know because I was there. Frankly it was an embarrassing show for them. Of all people Fred Durst & Limp Bizkit were the standout. The energy was all wrong. This was after their ill advised attempt to shut down file sharing & Napster. Plus the cuts from St Anger were just awful.
I'd been to their concerts before that. I saw them back in 2000 on their first Summer Sanatorium tour. They sold out the Georgia Dome in less than an hour & this was before you could get good tickets online; you had to show up at a Ticketmaster location and buy them.