Well, firstly, Madara wasn't pure evil. Thus far, no villain has been, discounting Zetsu, I don't know what to make of him at the moment. Though, I can say Madara isn't because he clearly intended to set up IT for everyone's happiness.
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Also, Kaguya isn't stealing his spotlight at all, she "orchestrated" all of Madara's plans really, just like he manipulated Obito so technically Madara stole her's. Though, it's disappointing that Kishi brings down a supposed "god" in such a way, he really needs to stay put on a single villain. I doubt Kaguya will be any special really. Just a bog standard villain with tits. Not a fan of either. :x