It doesn't "suck."
I'd be willing to bet that a lot of people are fans of the "Big 4", Metallica, Megadeth, Slayer, and Anthrax. A former Big 4 member, Testament, strattles the line between thrash and death with albums like The New Order and The Legacy while their later albums are heavy as hell and feature some great talent on the like DiGiorgio and Lombardo. Heavy Metal is also a lot more diverse than you think. Throw in something from Teutonic Thrash bands like Sodom or Destruction, then follow it up with some thrash/proto death like Possessed or Mercyful Fate, bring out the punk in you with something like D.R.I. or Suicidal Tendencies, take a trip to Florida(Immolation, Malevolent Creation, Death, etc.), go overseas with some up-and-coming band like Vader and top it all off with some Bay Area act like Metallica and some New York stuff(Overkill, Nuclear Assault.) Yep, it all sounds the "same".
Hey, I don't know a lot about funk, should I start a thread and complain about something I don't enjoy or understand?