Updated the original post with a hypothetical breakdown of some advanced class ideas Which can be found at >>> http://img535.imageshack.us/i/jobsfftstyle.png/ <<<

Personally, I am rather keen on the idea of requiring a gathering or crafting class to unlock advanced classes, even if they are only rank 10 or something. It makes players play a well rounded game. But I'm not married to the idea at all.