What people want is individuality. Everyone wants to be a little unique snowflake, and as of right now, you can't be. To give people the feeling of being unique, they need to make the classes more specific. The problem with simply adding "advanced jobs" is, with the current armory system, what would make them different from the current classes? If you were just mix and matching skills like you are now, you end up with the same problem. Also, you'd have to find a way to keep the current classes viable for use, so they're just not a barrier before getting to the "real" classes
I think the best way to handle this is to make "advanced" jobs more like specific XI-esq subjobs. Make it so, when being one of the current classes, you can pick a subjob out of 2 or 3 that are exclusive to that class. So, as a CON, you can be a CON-BLM, a CON-WHM,or a CON-RED. Each subjob would have specific skills exclusive to itself, and would not be transferable to other classes. For instance, as a base CON, you learn fire2 and ice2, and those skills would be equipable to any other base class, but as a CON-BLM, you can learn fire3 and ice3. However, you can only use those skills as a CON-BLM. That way, there would be a reason to level the current classes, but there would also be a sense of individuality between everyone's own character
Other ideas would be THM-GRM (Green mage), where you have a bigger focus on negative status debuffing, THM-TIM (Time mage), where you have a bigger focus on skills like Slow, Stop, Haste, etc
Opinions?