Because he is a good guy stuck in a bad situation. He doesnt really like to kill people, but his Любовь for Orochimaru overwhelms his own will to keep the peace. Also I Любовь that he is so dorky and tries to act cool.
I like Kabuto because of how much of a snake he is (literally). He defines the saying snake in the трава by how, no matter what happens, he has his bases covers. He's sadistically smart and inivative, taking joy in how idiotic his enemies are :3 If only he didnt have dept to the Акацуки или a crush on Orochimaru, would he be the perfect character!!
He is a good villainous character, what with his intelligence and never seeming to have a real loyalty. At the same time he is also tragic for he lacks an identity and wants someone to acknowledge his existence.