The reason Buffy's resurrection was an issue was because there was no guarantee that they'd be able to defeat the demon that came with her and there was no guarantee Buffy would come back as herself in the first place. As Spike implied, there was a chance she'd come back as some distorted version of herself which could be extremely dangerous. Or maybe the god(s) that Willow invoked would simply get pissed and smite them all. Basically, Willow was meddling with forces beyond her control and she bet the safety of the world on it because she couldn't cope with life without Buffy. That's why Giles was upset at her.
Later on they also had to deal with the fact that the entire process and everything it entailed left severe psychological scars on Buffy, but that wasn't a known factor going into the process.
Dawn doesn't have any such baggage attached. She was not created out of nothing, she was energy converted into a human being. But Dawn and the gang had no say or part in that process, that was something that the monks did without their input or knowledge. All the monks who helped create Dawn were murdered by Glory anyway, so there's nobody left to punish or feel any remorse. Nobody in the Scooby Gang did anything to bring about Dawn's existence and the threat that came along with her existence was simply that she could be used (against her will) by Glory to end the world. The gang responded to that issue (eventually) by killing Glory, so with that wrapped up there's nothing left to do. Dawn from that point forwards is just a normal kid whose existence is no threat or harm to anyone else, and there's nothing for any of the Gang to feel guilty about or to try to make amends for.
You could argue it was wrong of the monks to tamper with everybody's memories to make them care about Dawn, and that's valid. But again, Dawn had no say in that and all the monks are dead anyway. And, knowing what we know about Buffy, it's incredibly likely that she'd have agreed to protect an innocent girl regardless of the memories. Buffy of all people understands and sympathizes with a girl thrust into dangerous, unfair circumstances beyond her control.