They can't figure out what to do with Dragoon because there isn't a clear idea as to what kind of gameplay style they're even aiming for with Lancer and Dragoon.
The core Lancer abilities themselves are just a mishmash of archaic mechanics from 1.0 that they -tried- to translate into 2.0 and on. It wasn't bad in the beginning but it shows its age more now that the game has become a lot more active in terms of combat.
The problem is that Lancer and Dragoon are already established. Any change they make to -any- of the job's mechanics will go under heavy scrutiny from both development teams and the player base. There are people who like the core mechanics and do not want to see it changed drastically and vice versa. All the while worrying about balance issues, party compatibility, etc.
The first thing they need to do is figure out what they want the job to do in the first place. "Do combos and jump a bit" is not something they should base the job's tool set on.