Not trolling, please read this in a reasonable tone of voice:

Your idea was actually already implemented. It was called 1.0. Personally, I think that 1.0 had some fantastic ideas regarding classes, character level vs. class level and cross-class abilities. It suffered from poor execution, really horrible UI, and very, very little content.

Sadly, these ideas that I liked were totally killed when the problems overwhelmed them. The great ideas were then lumped in with everything that was wrong, causing the management change to the game. Then, when fixes were promised, people complained that with so many cross class abilities, they lacked a final fantasy feel and lacked a 'job identity.' Thus, we got the job system, the limited cross class skills, and the same people complaining about lack of customization/flexibility for their class/job.

*shrug* I agree with you mate, I do, but "This is why we can't have nice things."