1) You actually said it again... Dragoons and Monks who are playing their class, and using their abilities every single day know how to hit and attack and dodge properly without messing up their combo. You are literally talking about bad player skill with this point. Monks still out damage us on Titan or Ifrit with Greased Lighting falling off. Dragoons only need to position themselves for 2 hits, and it's a VERY easy positioning. Dodging might delay their hit for a second, but not interrupt it. And Any bad player will miss a move in a combo. That is an equal class fault, not a Dragoon/Monk only fault.

2) They can have good Sustain, not Great Sustain. I understand you want to fight for the tank class being the best class, but not even looking at potency of attacks, we can't deal our top end damage without pulling hate off the tank. AND NO, You can't do that in any boss fights and think it's "OK" because you are a tank class. If you turn titan for a Mountain Buster, you just killed the entire group. Or if you grabbed Cadecus, he will 1 shot you without Vitality gear on when you use your super strong burst. So then you look at Potency because the only way to DPS without pulling enmity, is using Storms Eye/Path combos.
150 -Heavy Swing
190 -Maim
270 -Storms Eye

Added together 610

Dragoon: (Without any positional effects)

150 -True Thrust
200 -Vorpal Thrust
300 -Full Thrust

Added up 650, and that is just their direct damage combo, So they can out Potency us with just that. However they have Better TP management, better enmity management, and another combo which adds a lot of extra damage on top of that.

(And yes Limit is parsed. I have my LS's Monk hitting for 19457 with Final Heaven)