The interesting thing is is that NiGHTS was supposed to be black slate, maybe not complete and utterly, it always had an air of carefree nature to it and it’s own past, but NiGHTS was always described as “Another you, within yourself.” NiGHTS is gender neutral so that anyone can impose their own on it, a point of the gameplay is that you become NiGHTS so that you can face your fears. Also NiGHTS into Dreams was about Claris and Elliot, not NiGHTS.
But, NiGHTS had a past with Nightmare, and people where heavily invested in it, so people imagined Nightmare from the nightmarens’ perspective, people became invested in the idea of NiGHTS being born somewhere it doesn’t want to be, doing something it doesn’t want to do,only to break free . While I think NiGHTS’s rebellion was always supposed to be admirable, and that it was supposed to be identifiable in some way, I think it was kind of just supposed to be bygones and Sonic Team didn’t expect it to elicit sympathy.
I wouldn’t be surprised if it’s largely thanks to the fandom that NiGHTS had it’s own side to the story in Journey of Dreams. Hell It’s thanks to the fandom actively rallying for it that Journey of Dreams happened at all.