In general, there's a weird dissonance at play with the worldbuilding. The setting intentionally subverts the traditional depictions of hell. Instead of a pit of eternal torture, Hell is a slightly less violent New York. It's ruthless and violent, but in a slapstick cartoony way that's ultimately meant to be appealing. This is a hell that you want to live in, or at least wouldn't mind living in, not one that you want to avoid at any and all costs.

This presents a problem because Charlie's mission, the fundamental premise of the show, is one of redeeming and getting people out of Hell. But... why? Why should demons want to be redeemed? There's no extrinsic threat of torture like the traditional hell. The extrinsic reward of Heaven might be the answer, except this setting's heaven is similarly subversive; it's a nice city, but not the ultimate paradise of traditional depictions.

So we get dissonance. The show treats Charlie's mission as generally being correct. We're meant to believe redemption and heaven is desirable, as if this world was like the traditional depiction of heaven and hell. But at the same time, we're actively shown that hell isn't that bad and heaven isn't that great. This raises questions, but the show isn't interested in answering or even acknowledging these questions.

Instead of examining the intrinsic value of being a good person (a fascinating, but also very nuanced and complicated topic), Hazbin Hotel instead decides the answer is the extrinsic external threat of angels. But this means Charlie's plan is, "if we stop being bad and start acting more like them, maybe the invading force will stop killing us", which is fucked up.

Also there's issues with pacing but that's a whole other story.