His was boring but none of the other loyalty missions had anything to do with the plot of the game. Except for Legion because at least the Geth were working for the Reapers.
Tali's loyalty mission took us to the Migrant fleet for the first time, gave us our first real look into quarrian culture and the possibility to sway opinion for or aginst a war with the geth. I'd say that's significant. Mordin's mission may also have very significant lasting repercussions. While the repercussions were strictly personal, Jack's mission served to remind the player just what kind of organization Cerberus is and just how many skeletons are lurking the the closet.
Granted the loyalty missions for Miranda, Thane's, Garrus and Samara didn't have much of a connection the the rest of the game plotwise, but they all served to advance their respective character arcs and deepen our understand of them. What did we get out of Jacob? His father was an arsehole. Whoopie.
With all the others you get a real sense that something in them has changed once they're "loyal." Either a weight has been lifted, or a new sense of purpose and meaning is found or a new perspective is gained. With Jacob you never get that there's anything dogging him (besides being Miranda's ex) until he the moment he mentions the distress beacon. What little angst he appeared to have seemed to be rooted in his frustration at Alliance and Citadel politics getting in the way what needs to be done. So some mission relating perhaps to his time as a corsair might have much easily addressed that. His daddy issues came out of nowhere and disappeared just as fast.