Multiple jobs is the way to go, no question. It is one of the selling points to the FF series.

That being said, for personal preference, there are times where I wish FF was a single class system. I am one of those people who really stick to one job, and don't really like to play much else often. In FF where you have the ability to have multiple jobs leveled, people will always gravitate towards class stacking and such, and it tends to force people into roles that they would not want to play. Even if I were to want to play Job X, but a fight was easier to win with Job A B and C, people will expect you to have Job A B or C leveled to do that fight because it is more convenient/efficient. I'm not saying all the time, but the majority of the time that is the case. It's annoying, and maybe ARR will do something to fix that problem, but that really is the main problem with the multiple job system that I can see anyway.