It’s not a heartless development, it’s harsh reality. That entire thing was simply to show that the way things are has twisted everyone’s perceptions of what’s wrong and right. I mean, c’mon, it’s an apocalypse. Is everyone supposed to be heroic to a fault? In my opinion, it only added to the show.
What he did was heartless, cruel, and downright asshole-ish, yes. But since Rick is considered the white knight in the beginning, the dramatic twists and turns of his development is meant to show that even the most just change for the worst in ways. And he’s not even completely void of compassion. He’s just lost all his trust in people outside of his group, his surroundings made him jaded.
The same goes for any of the other characters. Murrel is an asshole, a sadistic fuck that would just as easily gut a man as well as rape his daughter. But look at what he turns into in the end. He does something I didn’t think he could do. The shows not all about “lets make everyone slowly an asshole” it’s about an apocalypse and how they (the characters) cope with it.
Glen: nerdy, weak looking guy in the beginning. But through the course of the series, you see him toughen up and become more than the go to guy for scavenging supplies and see him become a viable leader of the group.
Carl (or Karl): soft hearted, scaredy cat kinda personality. You see him from a young age to now (bout 14-16 I believe) and he changes drastically. Season two, he couldn’t kill a walker. Season 3, he’s laying em down left and right. And he’s twisted with the world he’s in, just as any kid without a moral compass would do.
I think Daryl is the only character still alive that hasn’t changed too much, or had many things he does that paints him in a different light. Outside of[COLOR=‘Black’]killing his brother
Really, they aren’t becoming soulless assholes. They’re just becoming what it takes to survive. God knows why they didn’t save the hitchhiker, but it shows how everyone’s changed, for better or worse.