Obito the good guy, true hero
A nice theory would be, that Obito is still a good guy, and did all this, to save the world, and unite the villages, by becoming the World main vilain.
The enemy of my enemy is my friend.
He just gathered the Bijuus because Bijuus are, since Hashirama time , a source of wars and fights. By destroying the bijuus, he would unite all the world vs him. This is what happened.
He trolled us
Unfortunately I think he is just a basic vilain now, and we will get a happy end after Narutisation and betrail of Madara