I think that “more fps” is important when there’s things that move quickly compared to their size. My go-to game here is Batman: Arkham City - in the steel mill sections, there’s a lot of “sparky” particle effects; in general, there’s a lot of dust flying about. That stuff does look noticeably better at 90 fps than it does at 60 fps. My eyes can’t really see the difference at 120 fps, but I can definitely hear the GPU fans, so locked to 90 is fine. Makes absolutely no difference to the gameplay at all, of course.

Games that are designed for 30 fps tend not to have the same kind of particle effects, mostly because they would look terrible. I do feel sorry for the graphics artists having their hands tied, rather than being able to fully express themselves, but all engineering is about weighing things up and finding the right compromise, of course.

Yassifying all of your games with a slop filter is the complete opposite of artistic expression, of course.