I was a huge fan of Final Fantasy Tactics. Although I can't say I 100% agree with everything you posted here the concept of meeting prerequisites to open up certain classes in FFXIV is interesting. I have a feeling it would not go over well with a lot of people but I wouldn't mind it personally. It would also add more of a reason to level more than just one or two classes (which I think gives people a better understanding of how things work when in a party). Perhaps after you reach the required levels it would open up a quest to obtain the new class like in FFXI. I suppose I am biased towards it all though because I'm such a big Tactics and FFXI fan. Besides, it would make more sense; for example, for someone to summon a powerful monster/demon/god-like-thing (summoner) they would need to be experienced with the use of magic(s).