Bring back crowd control. Bring back branching dungeons. Bring back ADVENTURE.

[Lersayil]

No,they're not. People are adamant about how they don't want to spend too much time doing the dungeons. So, if having additionnal rewards can help you skip a run entirely, it's far from moot.
Instead of doing 5 20 minutes run to gain 5x90 tomestones you could do 3 30 minutes run to gain 3x 150 tomes, while also gaining more goetia tomestones, gils, seals, and chests at the end.

Your example saves roughly 10 minutes and 2 queue times. We are also presuming no other source of tomestones. It could work, but might lead to conflicts between those that just want to get the dungeon over with, with those that want to run it less (aka low queue vs high queue jobs).

Only if its effect is marginal, and that's mostly because dungeons are far too easy. Even right now Arm's Length slowing all ennemies make pulling lots of them far less stressful, as is holy spamming to stun them. These are already CC. Likewise, if you could paralyze all mobs so that they won't hit you as much, runs would go smoother.

Depends on what you mean by CC then. Most people here (including me) seem to presume you mean the classical hard CC (i.e sheep from wow, or Repose here). The kind that takes mobs out of the fight thus upping clear time. The ones you listed above provide damage reduction, but do not lengthen kill time.

Which could be fine, but if you make them mandatory it would bring a new can of different kind of meta worms of "have" and "have not" jobs. And lets be honest, I would not trust the average roulette runner to use such tools properly in a mandatory setting.