The thing with The Walking Dead is that it's really good at introducing characters in a cool way (who doesn't remember the first time we saw Michonne for example? That was badass) but they have zero clue on how to actually write interesting story arcs for the characters once they are introduced. Think about it. When you think about most of the characters on the show, the coolest parts about them are in most cases the first few episodes they appeared in, they made a memorable appearance when they showed up, and the plot became fairly focused on those characters as it introduced them. But the longer the time has gone by, those characters have just become bystanders.
I think even from the start, the writers have had major problems coming up with compelling character stories and arcs. What Morgan has gone through this season is almost beat for beat the exact same thing that Tyrese went through, when he had his phase of "violence won't help". Rick also went through something similar before that. It's like the characters only have two modes in this world, either they are passive bystanders who do nothing, or they go all out berserk mode. I feel like they have tried several times to do something different, but most of the times ended up failing. Like the return of the Governor. I remember liking his re-appearance initially because it looked like he was going to change as a character, but in the end he just reverted back to the same guy making the same mistakes.
But I think the fact that the show struggles with the characters is essentially its greatest downfall. They keep introducing us to new characters, because that's one of the few things they do really well (at least if it's a big character), but it worsens the situation that we already have too many characters and we can't give them enough screen time to actually develop them. I thought it was interesting to see Michonne before the outbreak, how she was then and how she ended up, but they didn't really do anything more with her story. Gabriel and his religious beliefs and how he was shaken by meeting Rick's group was also interesting, but he's been a passive bystander for this whole season so far. Abraham had an almost identical character to Gabriel and Hershel, with believing so hard in something that ultimately turned out to be wrong, and I thought it was interesting seeing Abraham deal with how his mission was a scam all along. But now he's just another passive bystander as well. When was the last time we saw Darryl have any character development? He had a nice dynamic with Beth and I would have liked to see them explore that a bit more, how he was affected by her death. He just basically travels around on his bike and kills walkers with his crossbow. I mean it's cool that he's a badass, but his character isn't really going anywhere.