I think this is what people are misreading in what I said. Even if they didn't go "omg yay, he's killing people" which is not what I meant anyways, they're going "hmm, well... I might as well root for Light". Since the toher characters haven't absorbed your attention or made the story interesting at all.
It's human nature, those with power are usually the only factors considered in sacrifice or anything. A king rules the country, the countrymen and servants die, but who cares who they were, the charismatic figure was the King and his speakers.