you can think those bands suck but you canot forbid me to use Atreyu & Metal in the same sentence... see : ATREYU HAS DONE ONE OF THE BEST METAL ALBUMS OF 2004

(& i really mean it !)
but i will have to agree on your comparison hardcore/punk for most of the hXc scene... great bands such as Refused, Sick Of It All, Snapcase have very little to do with metal not to say nothing...
one thing you forgot though, since Agnostic Front first introduced metal guitars on their "Cause for Alarm" album (that would be 1986 !) Metal & Hardcore scenes slowly became very intricate (for the worst when it comes to "nu metal".
now, in 2004, hardcore bands from germany (Caliban, Heaven Shall Burn) or the US (ATREYU !!! Unearth, Avenged Sevenfold) while keeping the spirit hardcore (more on lyrical content than anything else) play plain extreme Metal would you like it or not !
cheers & long live to Metal !