The option to become a rogue captain and stand apart from the federation and be out for yourself! All startreks are littered with "bent" starfleet captains and officers.....then later if so wished you could be turned good again!
It would be cool to warp into a fight and open fire on both Klingons and starfleet.....maybe hunter missions where you track a certain player and try to destroy them in pvp!
Also remember in the final frontier they were looking for God and found that giant head that screamed like a wounded cow? Well it would be cool to look for god and find the same planet but to find the head didn't die....once you kill it you get an uber drop!
And to keep the search for the planet real, once it has been found and completed it could change coordinates so other people still have to look....like the random systems you find in uncharted space!
You also have to kit out your ship to break through the great barrier that surrounds the planet!!