It focuses on the middle register, emphasizes the bass--which I love because bass rarely gets credit in heavier music--and it features gritty, robotic type of aggression. I would definitely agree that it appeals more to fans of Marilyn Manson and Nine Inch Nails than candy-flipping ravers in the UK.
Korn's single "Get Up" from their newest album The Path to Totality is the most commercial example of dubstep being forced into metal. Granted, Jonathan Davis has been saying the past couple years that Korn is "not metal and never was." But c'monnnn ... we all know that's not the case, regardless of the kilt. Korn paved the way for millions of metal fans, and is practically one of the gateway drugs to metal's purgatory.
So, right before the release of the album, Jonathan Davis claimed in an interview with MTV Hive, "Dubstep is the new metal. Metal shows are all hate, like, 'I'm going to fuck you up in the mosh pit.' Electronic shows are all peace and love. They rage harder than metal fans."
First off, I'm just going to pretend that this quote isn't from Jonathan Davis. Secondly, he may have just been super excited about his new "peace and love" album, where his most commercial single's chorus screams "shut the fuck up, get up."
"Get Up" was interesting -- far removed from dupstep's murky, atmospheric UK origins, but I think the dubstep breakdowns could have been more articulate and unique. The sound is now already being recycled through different metal bands and it's wearing quickly.
The problem with genres jumping on the dubstep wagon --metal is obviously not the only one -- is that we will soon grow tired of it. That's what happens when trends are manipulated, exploited, and overused. It seems fresh at first, after being underground for several years. Then, artists in new genres entice us to follow them with the smell of blood. It works for awhile -- just think of Autotune. During the last decade, it's gone from "this sounds sort of cool" to "this shit is annoying as hell."