Obito doesn't have his own body, his right side is white zetsu, so maybe that is whats causing him to look like this? And of course better control would have something to do with it. Compare it to Narutos chakra cloak and BM.
It mostly likely looked like the person it was the energy for, also to be noted, Obito's scars that he got from that rock as a child have DISAPPEARED, its like he has been healed and brought to life it just takes on the mazou skin
What i dont understand is now that there all in Obito, all the jinchurrikis that touched naruto are at loss to the . So it was really no meaning? I dont know anymore. It just made the manga like 10 chapters longer now.....