That’s a good question. I think it’s because they make really good use of their pixel style. You can see your character’s distinctive hair. And then after you do one jump, her hair turns white, and you can do one more action, but you can’t do the special jump. It’s all very clear, very to-the-point. The art is very clear, and it’s not hurtful to the eyes either.
By contrast, there is a game called Bloodstained: Curse of the Moon. Now that is truly hurtful to the eyes. The font is old style 16-bit font, along with 16-bit graphics, everything is so ugly, sound effects are old style horrible sounds. The controls are old school (they suck). It’s probably a great game for someone who can stand that stuff. But it makes for a nice contrast to something like Celeste. Celeste pretends to be old school, but the controls are not old school, they’re really precise. The sound effects are great. And yes, the art style has that pixelated look, but it conveys a lot more than those actual old games used to convey, because it’s way better than old school games used to be.