Yeah I see where you're coming from.
My reasoning for the game design choice was I wanted a storyline that wasn't focused on the romance side, even though I realize that's probably not the expectation most readers would have going into it. It's a friendship-first adventure, with a dash of romance as an optional bonus. It was important to me to make sure players spent time with all the characters instead of focusing in on only their favorite. My (imperfect) solution to this was the survival system as--like you mentioned--it made narrative sense for the characters to all train and learn together. But, yes, unfortunately this does lead to Vane getting a loooottt of attention. Even with some changes I made later in development to give him some "freebie" points, it never quite evened out just...lessened that steep dip to his side. And for someone who doesn't care for the character, I can see how this would be a slog.
I should have done more to fix that imbalance earlier on in development, and I'm truly sorry that this decision has created such a bitter gaming experience for you.