This changes nothing. Roy will always be awesome.
I'm not convinced that Emiko taking out a mass murderer is on the same level as those other things. It didn't feel inconsistent with her character in the moment. Sure, Ollie's softened her up a bit, but even he doesn't have quite the same hang-up about killing as Batman.
How does being a Deathstroke fan make you more qualified to judge if Emiko doing that felt out of place or of character? I gather you didn't care for it (it wasn't my favorite writing choice either), but that doesn't mean it was somehow contrived or out of left field. The other changes, especially with Wally, feel more deliberate as editorial pushes things in one direction or another, but Emiko's was born out her character. While I don't applaud her killing, I'm not shocked or dismayed by it as a step back for the character.
If DAMIAN killed that would be a step backwards.
Damian has had loads of character development since New 52 began. Ben Percy didn't know how to write him so he backpedaled a bit, but Glass has restored Damian's personality since. He's not just "that ex-assassin" kid anymore. People that really know him in the comics know that arrogant brattiness is a front, and that he DOES actually care about other people (and animals). To have him kill now would undo years of what Tomasi and Gleason did with the character, while having Emiko do it, once, in an extreme circumstance, doesn't ring false. Its not like Olliver's had long talks with her about not killing or anything, and she doesnt follow his lead as a sidekick either (she's her own hero).
I don't know. Over DC history, Green Arrow has had a far greater handful of kills than Batman—given that Batman has had none (or at least an extremely low number, but I’m pretty sure none) and GA has had a handful at all.
Damian killing again would have been a step back as Grimm suggested. He started off not possessing the moral compass that would prevent him from killing, but over time, he had developed a strong conviction against it, same as his father. He is still a bit rougher with criminals than most heroes, but he sees the line that he should not cross. When Emiko "went good," she knew that killing was not what heroes usually do, but she was not faced with the same "no killing" conviction that Damian was. So, of the two, while they both have a history with assassination, in terms of character development, it does make more sense for Emi to have done it than Damian. Plus, despite how arrogant he may be, Damian is not entirely independent. He does wish to seek his father's approval. He wants to honor his father's wishes because of that. Emi doesn't have a person she looks up to on the same level as Damian—especially not one who is as against killing as Batman is. Emi believes she was working toward the greater good, so she feels justified in her actions. Damian has long-since passed the point where he would feel similarly.
Oh no, Green Arrow is about 6 to Batman’s 1-2 in killing people. Without Black Canary to stop him that goes up pretty serious, maybe to an 8. He’s a hunter for a reason…
On a relatedish note, why hasn’t there been a Huntress Green Arrow team up? Other than it bothering Dinah, mostly from a lethal corruption standpoint but some may see it as something… else, I think they’d make a sick duo!
And now that I think about it we never get the chance to see many sweet male and female PLATONIC duos fight together! What’s up with that? Do people really put that much sexual tension pressure on that and that’s what stops them from being written or is a sexism thing or is it something else? There should really be more of those.
While I haven't read any of it because it's never been collected, I know for a fact that Ollie really went over the edge right before his death. He used killing as a first resort instead of a last. And we all know about that period right before Flashpoint...