Dru was Angel's trophy, 'his masterpiece', and one that he doesn't choose to end when he can, despite knowing that she will go on to kill more innocent people. There are a lot of occasions on both shows that vampires that they 'know' are allowed to live because of previous relationships/connections to them, either as vampires or who they were as humans. It never looks good, particularly with Spike, Dru and Harmony repeatedly being given passes, but it is consistent and a failing committed by many characters.It's a trophy, Spike's trophy, for murdering a slayer, and leaving her little boy orphaned in the process. Spike brags about that coat almost every chance he gets, because it's proof of his murderous superiority to anybody, especially a slayer, who crosses his path. It's how he swings his dick around, so to speak. No other vamp in the Buffy-verse really does this to the extent that Spike does. Angel doesn't have an article of clothing, or any other trophy for that matter, that comes close to meaning anything like that, and neither does Drusilla, Darla, hell, even the Master himself.
The coat was Spike's trophy for murdering Nikki, I'm not denying that at all, but you can't dismiss that he was choosing to not wear it at the start of S7 and that change in himself was directly linked to not relishing the fight any longer once souled. The coat was then used to reconnect to the violence in himself specifically to be useful in the fight. Yes, he had the chance to give the coat to Robin or apologise to Robin, but the guy had just violated Spike in retaliation by deliberately triggering him to override the person that he had become and access the monster again to fight. Robin knew already there was a meaningful separation which is why he told Spike he didn't want to fight him, he wanted to fight the monster that had killed his mother. Now I'm not saying I don't understand Robin's anger and hurt, I really do, but I also understand Spike's anger in that moment after he regains control. Having said that, I don't think he should have been as callous as he was, he took it too far, and although they both weren't treating the other fairly, it was Robin's grief over Spike having murdered his mother that was upsetting him, so Spike should have been more lenient and left the personal out of his attack. But neither of them comes out of the exchange well.
But the point in the episode is putting the mission above your emotions. Spike didn't want to wear the coat any more and have that connection with his murderous past, and he certainly wasn't happy about being told that his new souled self wasn't what was needed in the fight, but he did it to benefit the greater good. The message is deliberately an uncomfortable one here because the notion of putting anything/everything second to the mission is going to be uncomfortable and that is the point to be honest. It may well take characters places that they don't like and that don't make them look good but they aren't the priority. The episode deliberately aligns Spike's choice with both Buffy's request to him to be that person again despite his feelings on the matter, despite his soul, and also with Nikki's choice to go out at night and put herself on the line to fight despite having Robin - "the mission is what matters".This is the reason why I condemn Spike for wearing it: he had a CHANCE to change, to change his TREND, as I was saying previously, and didn't go thru with it, for whatever reason Team Spike wants to bring up (it's a weakness, an external prop he shouldn't use, Buffy told him to shape up, etc.) Fact is, he didn't have to pull himself together by putting it back on. He could've used a more morally uplifting way to do so (he DOES have a soul now, after all). In fact, he had a GREAT opportunity to make amends, to do the honorable thing, which would've been to either place the coat on top of Principal Wood's mom's grave, or give the coat back to Principal Wood himself and apologize for what he did. But NO, he didn't do that! He wore the coat again, knowing how wrong it was, because he has a soul now, knowing where it came from, and went right on punching and kicking. What the coat represents gives him the power to fight, and THAT is what's wrong. Where is this power coming from? Murder, mayhem, the old, soulless ways of doing things, which should NOT be his guiding light anymore, because he now has a soul, and has run outta excuses. He had the opportunity to rise above that, and did not, and that makes him simply despicable to me.
The meaning of the coat isn't his guiding light. Buffy, the slayer, told him that he needed to reconnect with the person he used to be and he did it in the way that he knows how. It wasn't something to work on gradually and create a new image to replace that could hold the same meaning as the old for him, it was an instruction to put on his big boy pants right now and get over the fact that he didn't want to be that person any longer and learn to be able to pull that side of himself to the fore as damn well needed. Now I understand why people don't like it, but it is the point of the story and the connection to the slayers he now has souled and fighting the good fight, what matters is the mission not the person. Now if you don't really want to consider in-story reasons that the writers (not 'team spike' ) created around the meaning of the coat and the push for Spike to wear it again, or perhaps you can accept an in-story reason but just dislike it anyway, that is of course completely your call. I know that I tend to lean more heavily on looking to the probable intention of the creators/writers than some fans do, turning to what could have been meant by the writing choices that were made, to increase character/plot understanding. As always, your mileage may vary, for others the stance of 'the author is dead' is the preferred point of view.
The comics are canon until Joss says that they aren't. He is choosing to keep having these stories written and not overwrite them with a live project. Until Joss actually declares the comics are no longer canon, what other projects he may or may not do aren't key. The canon comics are quite simply exactly that until then, and are Joss' current, active voice on the direction of the verse and its characters.
Spike can be an asshole but that isn't the absolute and only parameters of his person. He can make really bad calls and be deliberately cruel at times that are unnecessary. He has issues with being nasty/defensive and falls to this behaviour far too often, but he isn't alone in making mistakes and not holding his hands up to them. I don't understand why you keep saying Angel is a saint when he has made many dark choices with his soul perfectly in place. I'm not condemning him for the murders and the cruelty that he has displayed over the years because I can accept that he isn't flawless and he struggles with an internal balance of soul/demon which must be immensely difficult. Characters get it wrong, but we look to the overall path that they choose to walk for their intent and their abilities to keep developing and progressing themselves. Both vampires put themselves on the line time and again to help others and be heroic. They will no doubt both get it right and wrong many times again.and this proves my point! Spike is an asshole, which is why I'm not Team Spike but Team Angel, as Angel souled, as I've said before, is a saint, and a much better person to be in a relationship with, even though Angel can never be in a relationship