I don't know about boring, but it's incredibly cheap.
The core problem is not about killing or giving life. The problem is removing the character in ways that allow Naruto to avoid having to defend his choice. As far as the manga goes, that, above all else is what I want. Naruto never has to decide what next nor deal with any the consequences for letting them live.
Kishimoto obviously thinks letting him live is the more moral thing to do, but rather than taking it's most damning problem head on, he pretends it doesn't exist. Is there anyone who think that the best or more persuasive way to deal with a legitimate counter arguments is to pretend they don't exist? That's basically what he's doing,
it's total bull to take that stance and then cheat his way past the obvious problems with ass pulls and Deus Ex Machina..
There are a lot of things that I wish Kishi would focus on. The idea of punishment is one of those things for sure, additionally I just wonder how Naruto is going to change this ninja world. It seems that it's apparently magically going to change because everyone could read Naruto's thoughts and feel his awesome sense of compassion or something, but that's horrible. How will he change the world? How will he get a bunch of military communities to find other ways of dealing with each other? How will he prevent the consequences of war? How will he get said military villages to allocate enough money/resources/personnel to the ongoing victims of wars (orphans, farmers whose lands have been destroyed etc etc)? Kishi is great with the set-up, but with the follow through...
But then again, this manga is written for children, so I guess it's to be expected.