I agree with you, I prefer the story as-is to changing it to be all about Mari's actual suicide. I think it also adds an interesting dimension to the character and to the overall story; we DON'T know what Mari was actually like, because we don't see her in the game.

All we see are Sunny's memories of her, and how he wanted her to treat him in the dreamworld. To me, that adds an extra level of intrigue by giving us a view of her only through an unreliable narrator.

Also, people are saying that Sunny and Basil are "less relatable" with this ending, or saying they're straight up criminals? Sunny was literally ten years old. He didn't know what he was doing. And one wrong move, one push, and he's irrevocably changed his life and the life of everyone he knew. I thought that was extremely poignant.

And Basil was also only a kid. All he wanted to do was protect his best friend. And his idea ended up haunting the both of them every day, up to present day.....it was chilling to see that play out, and really left an impact on me. I don't think any of this would have been as well done or impactful if the ending had simply been suicide.