I've posted in other class vs job threads before, and here's my suggestions:

1. Have classes and jobs truly branch off from each other post level 30. THM gets THM only skills at 30+ whereas BLM can use all the sub-30 THM skills plus all the new abilities it learns at 30+. If they really want classes to have some utility, they need to make it to where they bring something totally different to the table than their job counterpart.

2. Get rid of the job stones and make job specific weapons. This would enable multiple jobs to branch off from classes and what you play is dictated by the specific weapon you have equipped.

I don't really care for the class system, because possibly apart from PvP, I don't see them being very useful in many situations. I feel jobs can solo just as well, if not better, than classes in most cases, so that's really not working in their favor either.