I don't really have a problem with Morty and Summer's fucked up morality, since they live in a universe where basically everyone has underlying misanthropic hatred toward everyone. They're just normal people in an evil universe, which means they are evil too by default. But they're like that because their victims of having to live their lives in a world that torments people until they lash out and they can't really do anything about that.
It's Rick that I think is wierd they keep trying to argue is not evil. Specifically I think the season 3 premiere. "Everything real turns fake, everything right is wrong. All you know is that you know nothing and he knows everything. And well, he's not a villain, Summer, but he shouldn't be your hero. He's more like a demon, or a super fucked-up god." They keep painting it like the possibility that he might care about Summer and Morty in some small moticrumical way means "Oh, well, he's not all that bad." For me, even if he does, he's still an excessively evil bastard.
And he just doesn't have as much of an excuse. The show implies that it's possible something fucked up happened to him to make him how he is like it does with everyone else, but even if that's true, Rick is among the most powerful people in this universe, to the point where he can take on an entire empire of his other selves with calm efficiency. The world he inhabits no longer has the power to hurt him the way it can others, but instead he just uses his power to cause untold harm into everyone else, in the end just becoming another agent of misery of the universe.
They already tried to play some stuff up for sympathy, like the season 2 finale where he turned himself in for his family, and I didn't feel much for him. Space Prison is where he belonged, even if it ultimately could not hope to hold him.