Looking back on it, you're right. Man it's been so long since I played V. I need to fix that.
But anyway, you could still switch jobs and secondary classes at any time, which allowed for experimentation without having to restart the entire game. And in X-2 and Lightning Returns (great game actually, if you're like me and like customizing classes in clever ways) you were constantly changing jobs mid-battle. Those things alone make them much more flexible.