My opinion as a creator can't be exactly from Player perspective, but I can share our motivation behind adding this decision. Some people prefer playing singleplayer games because it is less stress and more joy. Some people prefer adrenaline of playing PVP or multiplayer.
We have dating simulation game where the pace should be set by you as our Player. Some rewards might not feel strong when reached too fast, while slowing things down mathematically don't feel right so we added 3 variants of difficulty and tested them profoundly to offer experience to both sides of a coin - for people who want to experience fewer talks and then quickly see sex scenes and also for those who want to better know the character, and answer questions about the girl, to progress more, so the sexual content would feel closer to reality after talking together for a couple of days. We also worked hard on balancing it out so even on hard it won't feel too hard, but achievable if you casually want to play and still reach sex scenes within reasonable time.
PS: to give it a perspective imagine that on average if you talk to 10 girls and want to fuck 10 girls by reaching their sex scene it could take 60-70 mins on easy 90-120 on medium and 120-160on hard