Is it pointless to lvl Paladin?

[Phoenicia]

Also, (I could very well be wrong on this, so someone feel free to correct me if I am), but FoF makes a huge difference... etc.

You are correct, you got this very wrong. Correcting the math:

Buffs stack multiplicatively, meaning they apply one over the other. So when you say PLD in ShO uses FoF, they gain 30% damage of their new 80% damage output, putting them at 104% of base (not 110%). Considering FoF uptime (33% of the time), it's an avarage of 10% increase, in ShO that translates to 8% overall. You end up doing 88% of your base damage. If the fight has jumps and invulnerability phases, that can go slightly higher than that.

Now that that's established, let's compare PLD to WAR and DRK:

Grit DRK operates at 115% (Darkness) x 80% (Grit) or 92% of base damage. DRK's enmity multiplier is x5.5 on Powerslash (x6.5 with DA), and PS is 300 potency (40 higher than PLD). Regardless of fight phasing, DRK's DPS output is 92% of base. However DRK is capable of bursting through their ridiculous oGCDs.

Defiance WAR operates at 120% (maim) x 75% (defiance) or 90% of base damage. WAR has Unchained which increases their DPS by 33% (by dropping the 25% penalty from Defiance) and have the "best offensive CD" in Berserk's 50% damage increase. With buffs combined WAR is dealing 120% x 150% = 180% of base DPS. During this time not even DPS can catch up to WAR. Again, fight phasing can increase the uptime of these buffs, making WAR burst the stronger among the 3 tanks. Enmity multiplier is again x5.5 on Butcher's Block and BB has 280 potency (20 higher than PLD).

Based on the above:

PLD enmity on RoH: 260 x 5 = 1040. Or 1354 with FoF up.
DRK enmity on PS: 300 x 5.5 = 1650. or 1897.5 with Darkside. DRK unbuffed PS beats PLD's "fully buffed" RoH.
WAR enmity on BB: 280 x 5.5 = 1,540. 1848 with Maim, 2457.8 during Unchained, 2772 during zerk, and woopping 3686.8 during Unchain and Zerk.
Multiply all these numbers by 2.3 to know the total potency in tank stances.

EDIT: Very late edit, but fixed the potencies on Butcher Block.
Also, Berserk is 50% strength, which results DIRECTLY into 50% damage. Check up the formula by Dervy here.

The formula for Weapon Skills is:
((Potency*0.01005)*(WD*0.0400573+1)*(STR*0.1104171)*(DET*0.0001368+1)*BUFFS)-1

Adding 50% damage boost will replace the "BUFFS" part with 1.5. But since multiplication has distributive and associative properties, moving the 1.5 multiplier next to STR would affect it just the same, making the equation as follows:

((Potency*0.01005)*(WD*0.0400573+1)*(STR*0.1104171*1.5)*(DET*0.0001368+1)*1.2)-1

The red 1.5 is from zerk, the red 1.2 is from Maim. /END EDIT

So even if the PLD is doing nothing but RoH, the enmity multiplier and damage output allows DRK to stay ahead by simply throwing a PS combo every third combo (not counting in DA). WAR's optimal rotation alternates BB with SE combos. While WAR can drop its aggro combo for 4 combos after an unchained, zerked BB, they will still use BB as it is their optimal go to combo. PLD (and DRK) will never catch up to WAR.

From experience, the most trouble I had was in T10. At the time, the PLD was 2 ilvs ahead of me on the left side and wore fully melded accessories against my mix of 3 VIT and 2 STR accessories. I MT'd as WAR and my PLD went SwO, the PLD was doing 385 DPS and I roughly 350 by dropping Defiance off and on (to mitigate Critical Rips). By the time he got dangerously close to me in aggro unchained was back up and I would re-establish my enmity lead.

Morale of the story: At the same gear and item level, PLD, at any point in time and all level ranges, will never beat DRK's enmity. The only time PLD beats WAR's enmity is between the levels 26 and 30 since PLD gets RoH and DRK gets PS at 26, while WAR gets BB at 30.

Back on topic however...

Enmity is no pissing contest. It doesn't matter which tank has more enmity as long as the only other class that can pull enmity from you is also a tank.

Enmity is only an "issue" if someone who shouldn't have it can have it. Read; It is only an issue if your tank going all out can't hold it again a non-tank going all out.

The above, however, is not an issue since a PLD doing RoH in FoF will never lose enmity to DRG/MNK/BLM bursts, and PLD using Flash 3 times will have enough enmity to hold again a SMN using Raging Strikes + Dreadwyrm Trance + Tri-Disaster + Bane + Painflare x 2 + Deathflare (the highest AoE DPS in the game currently).

Who cares if a WAR in defiance will rip off Cenus or Echidna or Lyuba off you? If the WAR in the other alliance in VA wants to flaunt his e-peen at you by showing you he can generate more aggro, let him have the boss, switch to SwO, relax and DPS while he deals with main tanking silly bosses. You still win the fight.

As for raid setups and statics you should be communicating with your other tank and members as to who should tank what and when.

As for Paladin viability, it is a great class. Lackluster? Maybe. It has some of the strongest CDs in the game. They're a bit long and are meant to be used on their own. Unlike WAR and DRK who work by stacking multiple (shorter) CDs or require healer help to get a similar effects. Just be mindful that PLD's mitigation isn't that far ahead of the other tanks (if at all). However, PLD's mitigation is consistent and reliable (aside from the shield which is RNG or a bit iffy to time with Sheltron). Hallowed Ground for example will always give you its 100% mitigation effect and then continue off with your HP levels where you started, whereas Living Dead and Holmgang only work if the DRK/WAR are under the threat of dying (actually reaching the 1 HP). PLD wouldn't require the healer attention while DRK would die without healer intervention. While WAR can buffer his HP back up with Inner Beast, Equilibrium and Thrill of Battle, it wouldn't stay alive for long without healer input again. Also Holmgang is arguably the worst option among the three because of the self root and target requirement.

Again, play the class you like the most. Be it because of the aesthetics, class theme, play mechanics or whatever. A class you're passionate about would probably allow you to get creative with to achieve similar levels of efficiency as the other classes. Which is a lot better than forcing yourself to play a class which you don't like and would just have you spend the bare minimum to reach "acceptable performance".

EDIT: Very late edit to correct the potency on Butcher Block.