But why must WE see that, Darth?

You might say "to see how fucked up they are", but that's not true. They're depicted way too friendly for that. No, the real reason is that the author "likes" his villains and doesn't want to kill them. That's why the keep getting away. That's why they're having innocent fun when they're not out killing people. It's that. Bleach did the same shit. Boku no Hero, too. And I hate that.