Yeah for speedruns I can understand, but if memorization is just as much a factor to merely progressing in the game as reaction and skill, that just smells of bad game design. Challenge is good, but that particular kind of challenge seems forced to me - it's unfair and is essentially a cop-out method of artificially lengthening games, IMO.
I don't know if any of this actually applies to MM9, so don't take this as a bash against it or any other particular game, but it does seem to be a relic of the NES era that a lot of people have acquired a taste for when they actually had the time to deal with that sort of BS when they were kids.