The characters in Deltarune exhibit far more apparent flaws than in Undertale. Or perhaps they’re made more "human," but in any case, they’re clearly not just virtuous. Just look at Toriel, King and Queen, or even Noelle, Susie, and Ralsei. Worse still, Kris is portrayed in a very ambiguous light (the Sword Route gives us plenty to analyze on that front).
This isn’t incidental, Toby likely made this choice to enable more narratively compelling alternatives. For me, the Weird Route is infinitely more interesting than the Genocide Route, which is highly caricatured. Given that, I don’t understand why some players insist on copying and pasting concepts from Undertale onto Deltarune. I think it’s deliberate, they cling to a comforting fiction.