Negan isn't the Governor. He has a sense of right and wrong and justice. He has a set of rules he's put in place and has his group live by, not all that dissimilar to Joe recently on the TV show. That doesn't mean he is a boy scout, but he isn't a psycho where anything goes like the Governor. Negan has stopped rapes, the Governor raped. I don't think Negan is 100% bad. I think his introduction was meant to build him up as a force to be reckoned with, but he could have just as easily taken out all of them instead of just Glenn if he wanted to. He could have easily killed Carl several times just to punish Rick. He actually wants a functioning society. He just wants to be in charge of it. You live by his laws and you do OK. You don't, you get an iron or maybe something worse. He didn't kill Glenn just for the heck of it, he had his reasons for doing it. And for a time Rick and his group briefly followed Negan's demands because of that event because they really didn't have any other options at the time.
And Rick wanting to keep Negan alive even though he is a murderer like we do in our current society is exactly the point. Rick wants to bring things back to the way they are now for us, the way they were for them. Yes, they live in a screwed up world where you need to kill constantly to survive. Rick wants to bring that to a stop as much as possible. If keeping murderers alive to live out prison sentences helps bring that back around in people's minds, then that is why he wants to do that. Negan's own set of laws would have put him to death had he and Rick been in opposite positions. Rick is trying to prove he (and his group) are better than that and that they don't need to be so vicious anymore. The zombies have become a background threat. Its the people that have been the main problem for the last little while. Once they get the colonies united and get a system of trade up and running, things could turn out for the better for them. Or at least that is Rick's hope. He believes that people as a whole are still good deep down. Everyone left a live has been hardened in order to survive, but they still are capable of returning to the way they were.
I can see what you mean though. I think the nature of comics doesn't exactly lend itself to long speeches and arguments and the kind of decision making you might have been hoping for in Maggie. If this was a novel there would have been time for that, but in a comic you have to keep things moving otherwise we still might be at Herschel's farm right now. Its a different kind of storytelling and sometimes things have to happen quicker than they might in reality to keep the story moving on. Its not like she immediately said yes though. She was against it at first and then came around to the idea Glenn might have been good enough to spare Negan's life. I'm sure Kirkman will get plenty of questions about this in the Letter Hacks in a month or two.
And for the record, if I were Rick, I would have taken Negan out. He's far to dangerous and unpredictable to keep alive. But as a reader I'm glad they didn't kill Negan off just yet. I think there are a lot of possibilities to play with with him still around. Its possible he might become a contributing member of society, but in the back of your mind you'll always be waiting and wondering when he'll make his move. I don't see this as Negan getting away with murder, but more as a stay of execution. He'll get what he deserves eventually, but not just yet. Who knows, maybe something more horrible than bleeding out or being shot in the head awaits for him in the future? Keeping him around may be a good thing for the group in the long run or it might be a very terrible one, but it will probably be far more interesting than if he had just died here. I'm still a little disappointed the Governor was taken out so early on. The great things about comic books in general are the returning bad guys. And due to the nature of the Walking Dead, that's not something they really get a chance to have. So it might be kind of cool to have a villain out there that could return at any time.
