I'm willing to bet that if he made the option to avoid the side chicks available, he'd be submerged by grievances of people saying "this update only lasted 5 minutes, scammer milker worst ever etc" because they skipped the side chick. (You can find some posts lamenting "We waited 6 months for that?" in this very thread, by the way)
Also, with its current structure and narration style, if the game only involved a single love interest, it would most likely turn stale - if it were all about MC and Emelie, the novelty and content would probably dry up quick. A modicum of variety is needed: hence, the other girls. There is a reason usually games involving a single love interest are written in the format of short stories: they can afford to concentrate on a single character, and then leave before they outstay their welcome. (Oh, and as was previously said, if the MC were not involved with the other girls' sexy times, someone would cry NTR - so, another lose-lose proposition)
Also, to me it's not a bad thing when an author decides to favor his own preferences, and not the audience's. Games built around the author's vision have a chance to be more focused, sincere and heartfelt, while games build by majority or by committee are usually bland and lacking purpose.