Oh, get real.
Do you know how often I've heard people trying to write off Heavy Metal? People said this back in 1992 when Nirvana was going through the roof. People said this in the early 80's when New Wave was the big fad.
Heavy Metal still reaches people around the globe. Just because the mainstream press decides that it's not cool anymore doesn't mean that it's dead. They continue to try to write it off and then some band (i.e. Pantera in 1994 with the release of
Far Beyond Driven) breaks into the charts with a high placement and everyone suddenly gets on the bandwagon, again. They're nothing but a bunch of trend followers trying to increase their bottom line. The end.
Yeah, Metal does incorporate other influences. If it didn't, I don't think it would have lasted as long as it has. Sure, some bands have more melody than others. Who cares?