i feel the reason most people choose to go full length rom hack, partly because they want to come across as if there writing a massive, epic tale (stuff like that happens alot in fanfics as well), and partly because they dont feel as if they can properly balance a shorter length game, most likely cause theres so few examples of shorter length stuff to work from.
though i wont say that i wouldnt mind seeing shorter length hacks, but id say to be cautios cause most shorter length stuff that first comes out, if this idea dose pick up, iss probably gonna be shit.