well it's his manga, he's the one who gave him the mokuton in the 1st place. So he uses his characters as he desires and we fans read and watch it with all enthusiasm because not everything goes our way hoping that it might. Although tobi was one hell of a character. Easily my fav villain...
Naturally yes, but at times the author does lose track of each character. So Tobi could've easily been one of the cases where kishi forgot something or had some alternative purposes. Like when RSM Naruto gave Tobi another heart to live, he could've easily waste one of his eyes for izanagi to create another one instead. But he needed to save that same eye to save Team 7 from Ash.
So my question arise on why wait till later for Mokuton or Six paths since there is no alternative purpose for it?
I guess he forgot is all. That's what I actually meant by him being afraid to pull out his full potential.