besides RDM, which jobs actually need these fancy gauges to function?

[Ephemiel]

Like the above said, Bard definitely needed it since it lets you track the new procs and tells you perfectly how much time left you have.

[Yurimi]

I absolutely hate the AST one. Before I could just watch my status effects to see what was going on now I have to watch a gauge on top of everything else which as a healer adding more things to distract me on top of HP bars buffs cooldowns the boss's cast bar and what is under my feet is the exact opposite of what I wanted.

[Rhindas]

I have a love/hate feeling for AST as I don't need it to tell me what the effects do, and thus just gets in my way, but I'm sure it helps new ones. SCH, however, is an eyesore. I immediately shrank that and moved it to where the Aetherflow buff icon used to be. Waste of space. I don't have the Faerie gauge yet to decide on that one...

[Cherie]

I can't really say the job bars are needed but they add a visual element so you don't have to stare tiny buff icons as much.

[Zarabeth]

It seems pretty useless on SMN and WHM.

[Tsukino]

It seems pretty useless on SMN and WHM.

It's pretty pointless on WHM, but on SMN it actually came with a set of nerfs/adjustments. Can't use Aetherflow or any abilities that require stacks while either waiting for or in Dreadwyrm Trance, if Aethertrail is taking up any spots that many Aetherflow stacks cannot be replenished, and failing to land an Aetherflow-based ability removes the ability to get to three Aethertrail without reusing the whole chain.

I know it's all part of rebalancing, but it certainly feels like we lost a lot of functionality and replaced it with a shiny gauge.

[Chukkaque]

In general the gauges are there to make keeping track of tasks easier on all jobs. in 3.xx the skill gap between hardcore and casual was rather extreme and it was mostly due to the "intense" nature that 3.xx added to rotations.
As such these gauges are there to assist in keeping track of various aspects of jobs easier.

[Katryn]

Whm's probably isn't the most needed, but as someone who does use direct heals as part of my toolkit, I'm glad to have a quick and easy way to ensure I use my lilies at the best time possible.

[Amelia_Pond_Behemoth]

I feel with DRK, the bar isn't necessary. I just need the numbers and I'm good.

[SaitoHikari]

Bard MUST pay attention to their gauge, it's fairly clear the entire job was redesigned around their existence. A Bard that doesn't pay attention would essentially be missing the entire point of the job in the first place.

The split second decision making we have to make to maximize our damage output is pretty insane, and the gauges are also the reason why Bard DoTs got buffed to 30 seconds. It's a delicate balance between deciding whether or not you should throw DoTs on more enemies hoping for more procs, or go into blazing machine gun mode.

Honestly, I feel SB Bard is actually harder to optimize than HW Bard, but failure to optimize SB Bard doesn't result in your DPS dropping as much compared to HW Bard.