They don't love Dawn by necessity through their association with Buffy. They love her because they have false memories of Dawn always being there. They literally just met Dawn in S5 but that's not their reality, that's ours the viewers because our memories weren't rewritten. Buffy declaring 'We are family' to Tara's family was much better because it involved choice. Dawn's situation didn't involve choice. All these people were literally re-programmed to care about her. That's the problem and why your way of looking at it doesn't work for me. You can only chose your family if you are given a choice. Which Buffy & Co. weren't where Dawn is concerned.Back to your questions, in my perspective Dawn is another family member just like Joyce, I did not feel the central role of the Scoobies were displaced in Buffy's eyes, by necessity they love Dawn and Joyce like they love Buffy, why would it make their adopted family weaker? that sounds more in the vein of isolate someone to have them to yourself, which is not love. Dawn's story line complements "You choose your family theme" and really authorial intent takes precedence sometimes, that is the way it is meant to be taken.
Dawn doesn't work as a concept for me. In any way, shape or form. But I don't care one way or the other about her character. And I'm confused as to what hating Dawn has to do with loving Buffy, either the show or the character. A viewer doesn't have swallow every cool aid a show wants them to drink. I know plenty of people who are like me for example (no they aren't on this board), they draw the line in the show between S4 and S5 and view it as two separate things. Precisely because the concept of Dawn simply doesn't work for them.Some still find Dawn annoying even after all these years, that to me is the success of the writing in a admittedly weird way. I can't imagine anyone actually "hates" Dawn, that would make them no friend to or lover of Buffy.
Buffy choosing someone who she knows is a fake over not just her own friends (by threatening to KILL them) and chosen family but billions of humans on the planet, doesn't sound like Buffy to me. Buffy was still choosing Dawn even when Dawn was ready to sacrifice herself. Which was nuts because Dawn is in the world, so if Buffy doesn't let Dawn jump then the world goes bye bye and Dawn does too. No world, no Dawn. That's why I'm sure Buffy is programmed to protect Dawn (whether she truly loves/accepts her as her sister or not) above everything else. Even when it's insane in that Dawn not jumping also kills Dawn.I completely understand the point about false memories equaling affection and the duty to protect the word, I guess I just imagine, after Buffy initially found out the truth and rejected Dawn "You stay away from my mother!" she did have a choice, not to reject her duty to protect Dawn/the world per se (Although, she did say, if Dawn dies then I quite, so there is free will there) but to reject her as a real sister. For the question o erasing Dawn by magical means like Willow threatened, technically if it is by magic Willow or any one else could blink any person out of existence or fiddle with memories.
When Jonathon changed the world in S4 we were told it was wrong. Because it's wrong to change the world to accommodate one person. It doesn't matter that Jonathon did it for selfish reasons, it's wrong period. The monks shouldn't have turned the key into something that bleeds if blood is needed for the ritual. They should have used their power to toss Gory through a portal themselves. Instead they changed the world and forced a child on an unsuspecting family and put that child, the family and anyone close to them in mortal danger.In regards to Dawn two wrongs don't make a right. Does that mean Dawn was a wrong? well it is ambiguous, they were trying to protect the world from Glory but now that Dawn herself exists, that is not up for debate anymore "It doesn't matter how you come into the world"
If Dawn was a real human, Willow wouldn't be able to turn her back into her original form. And for the record (depending on where you stand regarding them being canon), magic was destroyed in the comics, yes. And what do you know...Dawn actually fades out of existence. And not only does she forget her own memories while fading, all the false memories others have of her also go bye bye. A 100% real, flesh and blood human exists in the world whether magic is there or not. Therefore Dawn was never real so it's not murder or whatever else you insinuate. Dawn's human appearance is a magical construct that only stays in place if magic exists."If Magic never existed or if it didn't exist anymore" is a moot question. Buffy doesn't live in the "Normal Again" world, she lives in a world with magic and with demons.
Wishing for magic to disappear would, well, take magic and have consequences like we saw in "The Wish" or like the false upraising like in "Gingerbread" demons are apart of the world. (magic disappears in comics correct? I don't know what happens to Dawn, it is a nonsequitur, anyways, magic exists and Dawn exists, taking Dawn out of existence by way of magic is akin to murder as putting into existence could be akin to rape, but to muddle with peoples life's without their consent is plainly wrong and two wrongs will not make something right again)
I see it differently. Not only is S5 booooring and filled with retcons and OOC nonsense. But the whole story arc for that Season is nonsensical, stupid, riddled with holes so big you can drive a truck through and 2 people we know and love die for someone we barely even know. Talk about unsatisfying.Regardless if it i your favorite season five is brilliant, it is not shoddily written as something like Connors existence and written off the show arguably is, on the show season five addresses every question that is raised.