Even Loveless adds flair to the world of FF7 as a whole, as much as many people hate hearing it.
And I don't mean only its message foreshadowing the fallout of the big trio's friendly relationship and the permanent death of least one of them, with a fight set at the end between the remaining two (or figures representing them, e.g.: anyone holding the Buster Sword standing as Angeal's legacy) and a sacrifice (as theorized by Genesis).
Loveless in FF7's universe is a book, a theater play with massive posters for all to see in Midgar and a topic of discussion worthy enough that it has its own in-universe fandom! (Granted, that's also part of Genesis' fandom and ultimately joins back with the main fanclub for him, but for a great deal of the story, they're the Study Group.)
It's certainly a beloved piece of media with an unclear/unfinished ending, though rumored to have one, that multiple key characters (Cid, Kunsel, Genesis, Hojo, even Zack, though unwilling) end up interacting with at one point or another of the story, with their own conclusions about it and its worth. (Hojo calls it "worthless drivel", while Genesis obsesses about it to the point it's probably his source of comfort as his mind deteriorates and falls apart.)
Loveless is a means of entertainment, just as the Honeybee Inn, the Gold Saucer, the gym, gardening or that playground with the fun slider you can slide on (heh) in the Remake.
Just like Genesis himself, it isn't a thing for everyone, I get it. But it's important that it's there, even if it may sound silly to say it. It makes the world more alive, by giving it a form of media that characters can like, dislike or feel neutral about.
And I even risk saying that it's one of the things that makes Genesis so unique of a villain, rather than being just some sort of "Sephiroth stand-in for Zack". He's absolutely losing his mind and becoming even more of a bastard than he was before (which he really was, for the sake of trying to prove himself as a match to Sephiroth and probably out of frustration that he couldn't be, despite trying so hard) but he has this one thing that he's extremely passionate about that doesn't really involve the world's destruction, at least not at first. He wants to find meaning in it, wants to find how it ends... But it just so happens that this one hobby of his also lines up with trying to find a cure for himself, while taking revenge on Shinra.
If anything, it makes him a lot more like what Cloud would probably be as a villain than what Sephiroth's like. (See: AC Cloud, mentally falling apart due to the weight of the circumstances, but still trying to look for a cure, still doing his own solo research.)
But well, this is getting too long and I'm on my phone, so I leave y'all with this: Genesis doesn't ruin any "nostalgia" scenes or retcons them in any way. He merely adds an extra layer to the unreliable narration of other characters and makes their turning points in the narrative much more believable and certainly much more human. It's actually a lot of his and Angeal's characters arcs, really; what really means to be human vs being a monster!
Long live our trashlord! I'm thankful he's there!
