Well I'm not a dev but as far as I know, implementing such thing would be extremely complicated. Why? Because pretty much all choices modify skills or relationship with the others characters. So, if there was an ability to get to the newest content, how would it add all the skills and relationships points that you would gain in a normal run? Would it choose randomly? Or go for preset routes? As I also suffered from saves not working, I can understand how a chapter select menu would be fantastic, but yeah it just impractical-the game isn't linear (on a choice basis) enough to make it work.
Buuut again I am not a dev :P