I have issues with the Darkside Aura, but it has less to do with the visual of the Aura but more that it is not the traditional sort of CD where you'd get one. Off-topic slightly but considering yal are discussing this,

I consider other Jobs' Auras.

Greased Lightning, Wrath Stacks, and Blood of the Dragon are the three different Auras that come to my mind. All three are IMO justified Auras, and they wear-off when not fighting. SE's comment about the Blue Flames effect looking bad when mounted I agree with - since these other three Auras also look funky mounted (especially Infuriated, less so GL), but the difference between these Auras/Buffs and Darkside is the former will dissipate soon after mounting (since you're out of combat - they wear off), but Darkside won't. Darkside actually does the opposite of fall-off when out of combat.

I like the tease SE offered with regard to the blue flames in the last Q&A. A Blue Flames Aura could be added to DRK in the future, but they'll be assigned to a different CD/Mechanic. Whatever that CD/Mechanic may be, having that combined with Darkside for the 'desired' Aura visual people want - I like that - especially if it's a CD/Mechanic that works like the others I mentioned - requiring combat in order to maintain.

Anyways, I like Auras IF* they're in good taste and IF* there is a rhyme-and-reason to their purpose. If PLD had a Spell/WS that required in-combat use to maintain, I think that Spell/WS would make for a justifiable Aura. Right now though Divine Veil's healing trigger requirement seems to make the most sense. Auras for just standing around AFK? I'd prefer not, not unless there's some in-combat requirement to maintain it so that it will otherwise wear off.

But different strokes for different folks.