well, i cannot agree on that. Game is called Hypnosis, main plot device is hypnosis of girls, harem is build exactly because of hypnosis because without it some girls were not interested in MC, some would not agree on being in harem, some would not have sex with MC at all and some were even lesbians. So no, without hypnosis this game would be far from where we are now. Also, BE could be done on any other way, like for example some pills. Would this game looks this same without it? No. Girls would take pills, say thanks, give BJ or two to get more pills and say goodbye.
Also hypnosis is so much more important here - interactions between girls are created using it and entire story of what happens when Watch is lost, its results and character development are crucial to current ending and to one before - Ship Cruise. That story would also not exist without hypnosis elements.
Also, up to watch being lost hypnosis was done every few scenes, right now you don't see it but before those side endings it was all around.
As a patron for early releases I have seen a LOT of Mind Control in game called Hypnosis clearly advertised as being strongly about hypnotizing girls. And when abruptly after year of development and numerous releases DEV take it away for a year or even more I am voicing my fully justified disapproval