What you said about the ML is true, he is not a good person like the other ML of that author.
The MC did think about the original and tried his best to avenge him. And having a second chance as another man in a totally different body, in a difficult situation is not easy.
I think the author must have made the decision early on that the real Siwon was a minor character at best and that he should be forgotten because he's dead now and this story isn't really about him. All that's important is his body (which the MC inhabits) and his background because it's important to how the MC will be treated/looked at in his new life ^^;; (not saying it's right, just saying...).
The ML is a morally grey-black character that doesn't care about ANYONE in existence except for Taemin so it's not surprising he didn't care about/looked down on Siwon (when he didn't yet know it was now Taemin at this point).
If anyone should have cared about the old Siwon though it really should have been the MC. I mean sure he's a stranger to him but hey you didn't have to die and got a second chance at life thanks to this guy (even if it wasn't something consciously done). Like get justice for him as thanks and in memory of a fallen human being ;;A;;
The brother really is irredeemable...I think everyone agrees the bad guys didn't really have to pay :( I almost wish that if the author didn't plan to make the criminals pay, that we wouldn't have gotten to know so much about Siwon's background (scenes and everything). Why torture us readers? DX
Maybe there just wasn't enough time to address it, focus on it idk I feel you though... ):
I'm still so fucking mad no one seems to care about Original Siwon. Like the Ml is all obsessed about taemji this taemin that. When they were together in that one room he called the bodie a slut and kicked him cause he didn't yet know it was Taemin. He already has so many bullies, why you being a bitch and worsening the original's situation.
Then watching the video with the rape he says it's cringe. As if that wasn't about another person being driven to a corner. Once again. Ahh but now this is Taemin so I care. Fuck off.
Second. The MC. Good for you that you got a second chance. A little more empathy. Bit brother still was so dismissive of what happened to the original. I'm so pissed.
Third. The fucking brother. That fucking whore. Got a inferiority complex and made it everyone's problem. Feeling like you are less? Use the time you spend with bad companies and improve yourself. Talk to your brother that loves you and supports you.Fucking deepshit. Hope you kill yourself too.
Finally. Why is there no real punishment huh? What was the author trying to do? Make it realistic? There are people coming from the dead switching bodies. Not very realistic. Get rid of these two.
And what about the adults? The teachers? I know Korea prides itself with the high suicide rates among students but god fucking lord. I'm so angry about this whole story. Read It like 6years ago and it wasn't this bad.