Naruto:
Naruto was really terrible, but I guess most everybody knows that. Still, three separate characters doing a complete 180° in terms of their motivations within the span of a chapter… that's something else, even by recent Naruto standards. My only guess is that Kishi couldn't figure out how to or didn't want to put the time and effort into creating believable reversals for these characters, so instead he just decided to just say "Fuck it" and get them all over with at once. That's the only explanation I can even slightly comprehend.
Of course, that still doesn't explain Karin. First of all, she doesn't even really need to be included in the upcoming battle. She's not a strong combatant, and I'm pretty sure that almost nobody actually gives a shit about her. However, even if he did want to include her, there was an easy way to do it without totally blowing the limited character development she's had. Just have her tail Sasuke's group. I mean, she's got fucking chakra sensing powers. That is basically all she's good for, and since that was enough for Orochimaru and Sasuke to find her useful (and apparently Tobi also called her "helpful?) she must be pretty fucking good with them. She can also totally hide her own Chakra. So why not have her tail Sasuke and the zombikages without their knowledge until they reach the battle, and then grudgingly step in to help when somebody's in a tight spot. Could be Sasuke who she helps out, if Kishi really still wants to maintain that crush. Alternatively, go the more interesting route and have her save Jugo and/or Suigetsu. Could lead to a more meaningful relationship with one or both of them, which could be either platonic or romantic (well, probably not romantic with both of them). Setting that up would hardly take any more effort on Kishimoto's part, and would allow for the development of some pretty sorely undeveloped characters. Or not, if Kishi was feeling lazy. Even if it didn't lead to shit, it still would have been better than what we got.
Bleach:
I don't have much to say about Bleach itself. It was an alright chapter, but it wasn't particularly interesting. However, I do have something to say about all the talk of cousin/cousin marriage in this thread. Basically, cousin/cousin marriage is totally okay and it's silly for you guys to be bothered about it. It's perfectly legal in a ton of countries around the world, including Japan, and a number of US states.
See all the blue in those two maps? Those are all the places that allow cousins to marry. It's not Japan that's weird for allowing it. It's the US that's weird for stigmatizing and, in some places, banning it. Frankly, there's no good reason not to allow it. Genetically, the risks are minor, unless it's done for generation after generation (leading to inbreeding). The children of two first cousins have a 1.7% to 2.8% higher risk of birth defects. That's about the same increase in risk for a woman having a child at 41 compared to her having a child at 30. As far as I know, there's no laws or significant stigma against women over 40 having children, nor should there be. Relationships with cousins should be treated the same way.
That said, there are tons of reasons to proscribe and stigmatize some other incestuous relationships. Sexual relationships between anyone and a significantly older relative (such as parents, aunts, uncles and grandparents) are almost sure to be imbalanced in terms of control, and are often abusive. Additionally, in relationships with closer relatives (parents, grandparents, siblings and blood-related aunts/uncles) even if such a relationship were to be totally fair and consensual, any children born of it would be at a significantly higher risk of genetic problems.
So yeah. Cousin-on-cousin action? Totally okay. We in the USA just have some silly laws and stigmas about it. Just about any other type of incest? Almost definitely not okay.