If it were just that I don't think people would have a problem with him. At least not as much. It's more that coupled with his arrogance and more so how you're expected to be totally fine with it because the plot proves him correct that he's the most awesome thing ever. So it's not just the arrogance, but the arrogance rewarded and the expectation that you should think it's omg awesome anyways.
There's also the fact that most of the first episode establishes a likable fellow that you think is going to be the protag then swerves and is like "dur-hur. No, it's the arrogant guy who's the main character. LOL." So unless you're just very invested in Tendou's inherent awesomeness then you kinda spend the show wishing it were about the other guy.
For me, I was willing to roll with that for a bit thinking that they would eventually have Tendou go through some experiences that would really cause him to get over himself. Sort of like the difference of how Domon in Gundam starts out as versus who he becomes in the middle and later parts of that series.
what's worse about Kabuto: It takes nine episodes for the likeable guy to get protag powers, and he gives them up one episode later out of "friendship" to Kabuto, a friendship that Kabuto doesn't reciprocate.
Although I really couldn't give a ****, I decided not to put the full word in the title for the respect of little children. And when I mean "little children," I mean grown internet users who still can't deal with the use of profanity because of their virgin minds (I would name a few =D but I won't).
Okay. No, I won't except Masato Kusaka/Kamen Rider Kaixa because everyone rips on him all the damn time. So pick someone else other than Kusaka (who probably would break/rape this thread with the most votes, hence the lack of a poll).
I mean...
Who would ignore that rape face and NOT call him an asshole/butt-wipe/dick-munch/other profane insults I can think of?
Me, I think...Mutsuki before properly sealing the Spider Undead. Yeah, so technically he was possessed. But I never had a character who really made it hard for me to finish a series.
So yeah, who do YOU hate with a passion that has the attitude that can match the KING of attitudes?
Nago, Nago, Nago, Nago, Nago. I am sick of people fangirling/boying him. Taiga and Otoya are almost as bad but at least Mio had the sense to try and kill Taiga, whereas Nago got Megumi and Otoya got TWO women. What kind of message is that to send to young viewers?