You vastly underestimate the effectiveness of Dragoon AoE and are probably doing it wrong, like 90% of pug!DRGs I run into. I regularly out-parse everyone but the top BLMs and SMNs in AoE pulls in either of the two expert dungeons. I pull 2000-2500 on any pull of 5 or more mobs if I use my buffs for it. 160 potency AoE that's spammable is the strongest single AoE skill in the game that's on the global cooldown and not owned by a caster. Anything more than 3 mobs, you should be Doom Spiking.
Now, if you're referring to A2, then yeah. Doom Spike is dumb there, where you should just be doing HT>CT>CT with gsk mixed in as your main AoE damage. And yeah, Dragoons are firmly in bracket 3, beaten out by [SMN] and [BLM/MNK] for overall dps in that turn, but they slot in right there with [BRD/MCH/DRG] before [NIN] picks up the rear.
Since I've gone into this at length multiple times in this thread and pointed to everything you've raised here as a counter argument, I'll just address each of those skills you mentioned.
Ferocity - Life Surge, but shitty.
Trammel - gimmicky move that will never be used. See: Freeze and/or Feint.
Moonrise - Enemies don't do TP regen. What would this do? Impact boss recast times? Let's make Dragoons even MORE attractive for raid groups.
Speed Surge - Basically Bloodbath, which is worthless. I'd rather not have another of those.
Twisting Vice - See: Moonrise.
Battle Regmen was a gameplay system which has no place in the meta of 3.0.
My main argument against giving Dragoons a "fifth" skill (since we already get 5...) is that we're ALREADY one of the highest DPS classes in the game AND we bring Battle Litany to the field, which is a huge gain for the party, believe it or not. If you gave us something else, it's gonna fall into one of these categories:
1. Messes with the current *beautiful* rotation, making things wonky and gross.
2. New utility move that makes Dragoons more attractive than they already are (90% of raid groups run one because BL+BRD/MCH buff).
3. New worthless skill like Feint that will *never* be used outside of certain situations which would actually still end up falling under 2 if it's *useful*.
4. New oGCD skill to boost our dps by a marginal amount we don't need to be boosted by while forcing us to squeeze YET ANOTHER skill into the first 24s of the fight.
None of those options are good. I want none of that.
Give me a legitimate thing we as Dragoons would WANT TO SEE as a fifth skill, and I'll maybe say your argument has merit. Every suggestion you made is either worthless or has no place in current meta. Sure they could be reworked for the current system, as I KNOW you'll argue, but how? Give me an idea that doesn't fall into one of the four shitty categories above and I'll listen.