obito is gone, just part of the story to explain kakashi's sharingan, and his view about leaving people behind, the story with obito made him the noble shinobi he is now, without that he would stick to the rules and be called a powerfull selfish basterd, a real tool because his actions could be easely predicted since he would folow the rules stricktly, but obito changed him in that repsect. other then that obito brings nothing to the story. he was a child with a newly awakend sharingan, but had no actual power or name to himself, and only half a body after his death, so why would anyone be interested in his body??
and even if he was alive, why would he have a grudge against konoha and the shinobi, why would he so suddenly be trying to take over the world, it just doesn't make sence.
it's quite simple:
madara managed to find a way to prolong his life, (with or without the help of zetsu, that is unclear),and being the briliant strategist and cunning shinobi managed to find himself a way to become very powerfull again and created a long term plan to gain al this power to get his vengence. but he didn't want people to target him while he was still reaserching and while he was in the early stages of his plan so he hides behind his alias "tobi" and orchestrates everything from the shadows by manipulating pain and that kage, and now sasuke. if he would stay under the name "madara" he would have been targetted all his life and would never have been able to complete his plan.
and he feels threathend by kabuto because he seems to know quite a lot more then others do.
that's why I belive tobi = madara and since the kage summit he finaly openly admitted it.
sorry for the spelling, I'm not native english and this was typed quicly because I'm getting a bit tired of all these obito theory's and I don't have much time at the moment
