“If everyone ends the story being buddy buddy with them I think that comes off as childish/unrealistic” I definitely agree with you there, it would be a bit strange if they’re all buddies by the end or there isn’t some kind of unease! To be honest the only villain I can see having a buddy buddy or shall we say mending their broken relationships by the end is Touya, given he has his family which I know their relationships are a bit….messed up but still there’s that. With Toga and Shigaraki I don’t really see whom they could be “buddy buddy” with by the end, and this is going off the assumption of the villains not dying by the end.

I think the reason many people think it’ll end with the LoV being besties with with some of the main cast by the end is simply that that’s how many redemption arcs end if the character doesn’t die. This is why people hate the idea of Endeavor having a redemption arc--because they think it’s going to end with everyone forgiving him in the end, either posthumously or not. And given that the story seems to be leaning toward a redemptive type ending for at least the main three LoV characters, that inevitably makes people assume they’ll be pals with everyone in the end (or at least with the characters who matter). 

Personally I think it’s to early to rule out redemptive death completely. I highly doubt Hori would kill Toga given he enjoys his Yuri bait to much, plus she hasn’t been shown to be physically/mentally at her limit to the point where her death would feel more expected. But Touya and Shigaraki could easily do the “sacrificed myself because I’m dying anyway” trope. 

People who are against this, say it would mean the Heroes, particularly Izuku and Shoto failed to save their villains--but that’s a very limited view on what saving can mean. As long as Izuku frees Shigaraki from AfO’s control, and Shoto manages to sooth Touya’s anger/hurt to the point where he can care again, then they are in a sense saved. I mean, in the end of Star Wars, Luke saves his father, but he still dies--that doesn't mean he failed.  

Touya and particularly Shigaraki dying is an easy way to end things and have it make sense. Again, redemptions usually end with people forgiving the character in question. The issue is that Hori didn't set up that dynamic in his story earlier, while also having the LoV double down constantly. There’s also the problem of Enji, and Bakugou’s arcs which are still ongoing and have racked up hundreds of chapters. 

Having the LoV change their minds in the last 50 chapters is hard enough to believe, but having the world (because their actions were shown to have global consequences) forgive them no problem just because they helped stop AfO, the guy they were helping without much complaint twenty-minutes ago, is even weirder. On top of that many people suspect Izuku will be Shigarak’s new bff along with Bakugou, while Aizawa becomes his father figure because Kurogiri tells him to as a dying request. And Ochacko and Himko are (girl)friends by the end as well. 

This isn’t me saying I’m against redemption arcs or even these over the top optimist/unrealistic ones, but they have to fit the story. Bnha has always shown with characters like Bakugou and Enji (or even Aoyama) that forgiveness takes work and no everyone will be 100% okay with you regardless. These characters that have for the most part done equal or less then the LoV in terms of harm,  fought and bled to be better people and even then don’t get hands held. So, if Hori does end it with everyone being pals I will call that some crap writing.