I still think one of the better things they could add would be detailed letter correspondence between Luna and Noct.
Show us why they love each other, and how they're always tuned into each other, and how they understand each other to a depth and degree unlike anyone else, despite the physical separation.
These letters could arrive via Umbra upon making camp or checking into a motel, once per chapter, for the first half of the game. In these letters, Noctis could bare his soul to Luna, mourning his dad's death, lamenting the pressure he feels as heir, etc. Luna could do her own emotional venting. We could also see a lighter, more playful side to the two lovers.
The letter cutscenes already in the game are so short and simple, functioning more like text messages: "Hey babe, be there soon, xoxoxo." That's fine, but let's see some of the in-depth correspondence they've allegedly maintained over the years. Let us peer into their head space and see their emotional connection so that certain developments later in the story carry more weight.
