What makes a good Job mechanically?

[Zairava]

Low skill floor, high skill ceiling. There shouldn't be one single set rotation for every job. Players should be able to have fun playing the job at a non-optimal and an optimal level.

A job should be able to keep the people engaged with the moment to moment gameplay, and have kit interactions (think Dark Arts and Darkside for DRK (HW/SB), Eukrasia, Kaiten, BLM's MP pool and power between [Astral] fire and [Umbral] ice and, RDM's black/white mana gauge, Mudra's->Ninjutsu (also Suiton->Trick Attack and Meisui), WHM's Blood Lily, etc)

If this means that certain groups of players will not play the job because they do not like it at it's core, that is okay. Not everyone is going to enjoy every single job, you don't even see everyone enjoying every job now, and this is the expansion with the most streamlined, samey job design we've had to date.