I tend to look at each game for what it was in it's time. They didn't really have ability to do what 5 and Tactics did back then, which maybe isn't such a bad thing as it's pretty difficult to abuse the system like you can in the others (though solo dragoon is pretty broken). Also, 3 isn't extremely dependent on the system for your success. When 3 originally came out it was a pretty impressive job system. It had extremely specialized fighting classes, special abilities, new types of magic (time, terrain, etc.) and the introduction of summons. The ability to change classes at will wasn't something anyone had ever really seen before. While I do agree 5 and Tactics have better systems by todays standards, 3 was very awesome and groundbreaking for its time.

just my 2 cents