F4 may have a different reason - but they are typically shunned because of their difficulty/frustration levels. Rayxanber 2 is a crazy, fast-paced memorizer that will make you want to punch a wall. Same goes for Image Fight 2, but I actually beat that one after a week or so of sticking with it and came away LOVING the shit out of it.
I've yet to crack Rayxanber 2 though, so hard.
If you like those old-school challenging/impossible games though, these both look and sound amazing. They're just....you know, balls hard.