As far as any normal rock band is concerned, most of the attention falls on the lead singer to carry the showmanship. Since you don't necessarily have an instrument in front of you, you're the person that everyone focuses on for entertainment, whether it be in the music videos or just hamming it up in interviews. Then again, being an extroverted showman isn't always a part of the job description when starting out.
Aside from a handful of classics under their respective belts, these artists have had a humungous albatross around their neck with the people they have out front. While some of these people might not be the worst singers or anything, they have put their foot in their mouth far too often for them to be taken seriously anymore. Even if the music itself still kicks ass, it's hard to really focus on it when you have the baggage of the singer in the back of your mind the whole time.
Hell, some of these frontmen aren't even that bad, but rather just a non presence in the lineup, taking up space where there should be some outrageous party animal or thoughtful intellectual. In a business that relies on stirring the audience up into a frenzy, the extracurriculars behind these artists have been leaving hardcore fans a bit cold for years.
The entire metal scene of the '90s owes Pantera a debt of gratitude for even coming into existence. For as much as the alternative revolution should have crushed any goodwill the genre had left, records like Cowboys From Hell and Vulgar Display of Power brought the heaviness back into rock and roll, complete with some of the most insane lead fills from Dimebag Darrell. Though Darrell was the nice guy everyone palled around with, the same couldn't be said for the frontman.
Granted, it's not like Phil Anselmo was looking to be a happy presence, with most of his live antics being centered around kids losing their minds and getting into serious altercations on more than a few occasions. When you actually look at how he comes off in interviews though, this isn't the same kind of amped up energy that you would get from your average metalhead.
Over the years, Phil has stirred up his fair share of dumb sh*t with the media, even going so far as to being called a racist after making a Nazi gesture during a tribute to Dimebag Darrell a few years back. Though the crux of the metal community is about headbangers coming together to have some fun, Anselmo just comes off as the school bully who wants to throw you against a locker and take all your lunch money.