Why can't we have jobs with this level of depth and customization in FFXIV?

[Risvertasashi]

Of course you weren't. You were just cherry-picking one of the two "complex" jobs of FFXI while calling FFXIV's rotations simplistic.

For that particular example, it's not the rotation, it's the setup and configuration possibilities.

There is already a job like this, it's called Scholar.

Contrary to popular belief, dedicated "support" classes (as in, a class that does nothing other than buff/debuff) are not only the biggest pain in the ass to balance in any game environment, but they require an existing system to undergo thousands of dollars in alterations to accommodate said change.

SCH is one of the most fascinating jobs in the game, IMO. I actually think SE did pretty well here. I've seen shielding/mitigating healers before, but not pet based healers.