Jobs are complex if you have to make decisions. When you have to adapt your rotation to the encounter. When you can fail at the job.

BLM has a simple rotation, but you constantly have to adapt to the encounter. Old DRK was easy enough to play but you constantly had to keep your mana in balance, decide how to spend it, not running dry and not overcapping. You had to decide what to do with the old AST cards when you were drawing something unfavourable.

Everything is so streamlined now that you can not fail anymore (Huton becomes a trait) and every inconvenience gets removed (no RNG AST cards anymore). The game plays itself now, you are just pressing the buttons.