Originally Posted by Emissary of Justice
Obito didn't use powers from Hashirama, Madara, or even Zetsu in that fight. It was all him. The only jutsu he performed were Tailed Beast Extraction, Kamui, and the Summoning Technique. He didn't own Minato either. Dude got his shit pushed in. Minato died that day because he wanted to, choosing to use the Death God so that Kushina could meet Naruto someday.
I would blame Kishi for this one. Initially, it was said that the masked man saw through everything Minato put forth and that it took someone with special abilities to be able to beat him. During the flash back, we saw otherwise; Minato was more concerned with maintaining the stability of the 5 great ninja villages, abiding by Jiriaya's prophecy, and perhaps obtaining his own satisfaction of having his son carrying the burden than stopping Tobi. Hell even the reasoning behind Minato coming to the idea that Tobi was Madara, was lacking, other than Tobi controlling the Fox (which can be done by any Uchiha if they've reached a certain dojutsu capability). I could see if Madara was recorded to have had space time techniques, but that just doesn't seem to be the case.
How that whole scenario played out coupled with what we were told in the beginning probably contributed to one of the biggest "whys" of part 2.