FF parties have always consisted of two groups. A few main characters, each with a deep plot of his/her own, and a second group of lesser characters. These members have little to no story, and on occasion, are completely useless in battle, too.
Now, I'm not referring to secret characters, as they are entirely optional, and are designed to be a treat for players. I'm referring to characters that 'make up the numbers'. Often, they exist only to occupy a space in battle that no other character can fill, but some aren't even particularly useful fighters.
Personally, I was never that fond of Strago or Relm in FFVI. Sure, they have high magic power, but at the point in the game at which you get them, they're so far behind the rest of your party in terms of magic they have learned. Their personalised abilities weren't particularly useful, either. Strago's Lores were not only time-consuming to learn, but little more than glorified versions of other attacks when you received them! As for Relm, the Sketch bug rather ruined her ability.
Of course, there are plenty of other characters like this. I don't really think they're pointless, they all have their moments. But some of them are perhaps unnecessary. Which character do you think an FF could have done without?