This drives back an idea about fairness in game design which relates to xmod charts as well. It comes down to "Is this chart/course sightreadable?" If you can't react to a note as you see it coming, then how is that fair?
Humans can theoretically only react as fast as about 130 milliseconds, and average reaction speed is about 230 milliseconds. The note that appears on the screen must not only appear for at least that long before hitting the receptor, but it must also travel in such a way that it is clear which receptor it will hit and when. If it should change trajectory for any reason, the player must have at least that much time to then reassess the note's trajectory.
People didn't know this many years ago, and despite some of the effects being really cool to watch, the charts were unplayable without pure memorization (like
Glitchcraft). Nowadays, I think people seem to be more aware of this.
So I don't have a problem with these modifiers
as long as they're fair, with a few exceptions, but those I probably hate for different reasons.