Because it has mature themes and violence.
Well, there are many reasons to why it's rated tv-ma.. 1. there much violence in the anime, if you have not watched the anime, there is much fighting, blood, and death, sometimes to were people who cant handle gore cant go with it. if you notice.. * SPOILER SPOILER * when Alois Trancy was stabbed by Ciel, there was a lot of blood. 2. there is many sexual things involving with this anime, cannon homo's, ( grell... ) and sexual jokes, and slight nudity. ( no nipples... just showy ) 3. it should be more rated to mature, even the plot of the story, can be a little haunting.
Ricky Gervais Out of England 2 - The Stand-Up Special - 2010 TV is rated/received certificates of: USA:TV-MA
The Tudors - 2007 Tears of Blood 2-2 is rated/received certificates of: Netherlands:16 Netherlands:12 (TV version) USA:TV-MA
John Adams - 2008 Independence 1-2 is rated/received certificates of: Australia:M USA:TV-MA (TV rating)
Teen Titans - 2003 is rated/received certificates of: Australia:PG Brazil:Livre Singapore:G USA:TV-Y7
American Horror Story - 2011 Nor'easter 2-3 is rated/received certificates of: Germany:16 (TV rating) USA:TV-MA
Co-Ed Confidential - 2007 The Bachelor Party 2-11 is rated/received certificates of: USA:TV-MA (TV rating)
The Tudors - 2007 Everything Is Beautiful 2-1 is rated/received certificates of: Netherlands:16 Netherlands:12 (TV version) USA:TV-MA
"Rosario + Vampire" is rated TV-MA, suitable for ages 18 and older. "The Melancholy of Haruhi Suzumiya" and "The Melancholy of Haruhi-chan Suzumiya" are rated TV-14, suitable for ages 14 and older. "Cardcaptor Sakura" and the movies are rated TV-G, suitable for all ages.
No. Hayate no Gotoku is its own animanga and 2 years older that Kuroshitsuji.
American Horror Story - 2011 Welcome to Briarcliff 2-1 is rated/received certificates of: Germany:16 (TV rating) USA:TV-MA
The Pillars of the Earth - 2010 Master Builder 1-2 is rated/received certificates of: Netherlands:16 Netherlands:12 (TV version) USA:TV-MA