I felt like this might help satisfy a desire across a few areas. From a RP standpoint, Achievement seekers, as well as getting people to try new things in the game.
Legacy Titles for the following:
With one of your next expansions, up the Crew Skill and add an achievement for doing a mission or crafting something X amount of times and get a Legacy Title such as;
Master of Investigations
Master of Diplomacy
ect.
2nd fold, Add Legacy titles for each spec of class. Have them need to do something in that spec to earn the Achievement such as
Combat Sentinel
Sentinel Watchman
ect.
This gives Legacy Titles to display which could apply to RP, but also appeals to the people who seek more achievements. On the plus side, you have people learning new classes, and specs, as well as trying out a variety of crew skills.