By the way, Anakin's child-killing has always struck me as the most despicable part of the prequel trilogy. It does not make sense on any level, and ruins the entire series. If, as Lucas made-up while justifying writing the prequels, the entire series is about the rise, fall, and redemption of Anakin Skywalker, child-killing puts Anakin in a morally reprehensible category cut-off from redemption; all for the sake of making it seem believable that Kenobi would want to kill him.
I get that Vader and the Empire have the Jedi Order enslaved and eliminated. That makes sense. Did they need to show that in some form? Probably. They could have shown Anakin tricking the younglings into being rounded-up and sent to some uncertain dismal fate. They could have made it happen later, by showing the new Empire enacting an anti-Jedi policy. They could have not shown Jedi children at all-- aren't they supposed to be really, really rare anyway?-- and just proceeded with slaughtering the adult Jedi, which would have done the trick. Did they need to show Anakin going into the school and killing every single Jedi "youngling" personally? Isn't this supposed to be a kid's movie? Wasn't that the excuse for Jar Jar Binks? What happened between then and Episode III? By the way, "youngling" is a pretty deplorable way of masking that child-killing is the content of the movie.
Anyway, this "youngling" slaughter creates a number of problems. It tricks the audience, as well as Kenobi, into adopting special moral dispensation for supporting the immediate killing of Anakin, over a bombastic lava-put fight. Lucas knows drama! It disqualifies Anakin Skywalker as a redeemable character, calling into question the so-called point of the entire series. It disqualifies Star Wars as an all-ages and, maybe more importantly, children's series. When I grew up watching the original trilogy, I looked up to heroes and moral paragons like Han Solo and Luke Skywalker who, despite their imperfections, are good role models. Meanwhile, Anakin Skywalker was marketed to children as the "hero" and relatable character from the very beginning. I shudder to think what it's like for kids growing up watching the prequels, looking up to Anakin as a role model and identifiable character despite his various unjustified slaughters in Episodes II and III. Adults understand Anakin's "violence is the answer" philosophy is not to be emulated; but do young kids? Anakin's entire descent into darkness was terrible, in my opinion. It was bad cinema, and it was wrong, morally, to disguise that type of movie as a kid's film. The prequel trilogy needed to be a much darker film, or a much lighter film overall. I guess it's money that rules Lucas' world, though!