In my opinion the problem is not that they need new inspiration for jobs.
the problem is we have a dev team that is not creatively competent enough to properly implement, and use the many jobs and ideas they already have, and until that problem is resolved other classes that are created will either be clones of already existing jobs in the game (like the entirety of the healer role, and basically the tank role), or the new classes will be confined to be limited jobs -- essentially making them unusable in any current content (like one of the most unique and expansive jobs in the franchise Blue mage...how on earth did they mess that one up -_-)