I've always disliked Kabuto... ok, so there were about five minutes during the Chuunin exams I could stomach him but that's about it. When we first find out he has added Oro DNA to himself and then ran off into the woods like a total nutcase, I was relieved. I was really happy because I thought that was the end of him. He was acting loony and took off, so I figured that he would have just remained bonkers, or the cells would take over his body, and we'd get Oro back. I despised the character to the point of making AMVs using "You have AIDS" from Family Guy, and "You're Pitiful" & "White and Nerdy" by Weird Al; oh and the A**hole Song by Dennis Leary.
So here it is that he is suddenly Trogdor the magnificent, and in some weird way that works for me.... because I didn't like him to begin with. By hating him so much it has added to the story now that he is a major villain. With that said, I don't care about his backstory, and even if I did we've wasted multiple issues on what could have been summed up in two pages. Besides the story didn't really tell us much more than we already knew.
The real problem with this is Kishi's story telling. He's got way too much going on that is integral to the plot, to just linger for weeks at a time on one person. If this were a movie, say Iron Man, and we were at the climax of the plot with Obediah and Tony fighting it out on the roof, and all of a sudden, they cut to Obediah's childhood, just to tell you what you already knew, plus one or two tidbits you didn't really care about, you'd probably be pissed. In fact it would ruin the movie.
Point is, considering we have a war, and three major character battles, there had better be a point to Kabuto's story. Besides, it's rather unnatural story telling. If I'm walking down the street and get into a fight I'm not going to be like "Time out. Before we proceed with the punching and kicking, I'm going to tell you what my childhood was like." That's crazy, and it would be even crazier if my opponent just stood around to listen instead of attacking me.
All I am really saying is that if the story has so many different things happening simultaneously, is this really the time to be dwelling over flashbacks and character details? By the time you are near the end of your plot you really should have had that hashed out already.