The easiest way to improve the gameplay would be to change the tone... add a little bit of violence, nothing over the top or gory, but like "gang of deliquents beats you up and messes up your stuff".
Though for anything like that to work they'd need to do something heretical, which is to have a more firm "default charlist" and a more story-driven/semi-linear? story, as well as have some kind of "pros and cons" list for the protagonist, at least in that default story-mode.
The reason I say this is because KK's story mode lacked any "tension" aside from double-dipping on a date, and even then, and you need some tension to make the gameplay somewhat memorable or for personalities to be able to differentiate themselves.
so for instance the deliquent personality should be willing, wanting, or able to beat the shit out of the player-character if he does something to offend her.. the Yandere-type should murder or at least threaten to out of jealousy.. etc.
a less saturated color pallet would also be nice but that's just me, looking at some of Illusions older games I kind of miss that "Homemate"-look where it's cell-shaded but it's also has some better default proportions.