I wouldn't say that Obli is a villain, but he is a villain. Although, I wouldn't fault him for it. After trying to find a way to bring back Neru for over a thousand years and having his hopes destroyed along the way, I can see why he is willing to sacrifice everything to reunite with Neru. You know what they say, a hero would sacrifice you to save the world, but a villain would sacrifice the world to save you.
But... I do wish that Roddorod focused a bit on it. I feel sympathetic toward Obli since, well, all methods of seeing Neru was gone, but I wouldn't say that I feel sad for him. To put it bluntly, the revelation didn't hit as hard compared to Prologue's ending. Even after many rereads over the Prologue, I still get teary when finishing it! (I'm only currently at the beginning of Chapter 2 of my rereading, so this statement might not hold. Also, can't wait for the new materials!)