Dragoons need to be buffed...

[Riichi]

Thats not how the math works though. When you miss your impulse drive that means you cant use your disembowel as planned next. Your rotation changes and because of that all the times on your buffs/debuffs and dots change, increasing the time it takes you to do your actual strong skills like full thrust or chaos thrust in your rotation, resulting in a higher loss in dps then just the missed potency of the actual positional attack. When a MNK misses his dragon kick you can still do twin snakes/true strike next in your rotation as if nothing happened, so its really "just" a potency loss for MNKs while in DRGs case its not.

I'll let you in on an ancient Dragoon secret on Heavy Thrust. Ready? If you miss....cast it again...
I've taken the liberty of constructing a nice, visual mathematical representation for you so you can hopefully understand it.
Here's your ideal combo without buffs/weaving, since that wouldn't matter anyways. Underneath that will be a combo with a missed HT at the start with the same amount of GCD's used. (Filler TT at the end of first for equal GCD use)

HT + HT+ ID + DB +CT+ PHB+TT + VT +FT+ HT +TT + VT +FT
170+180+220+500+320+150+200+330+170+150+200+330+150 = 3070 potency
100+170+180+220+500+320+150+200+330+170+150+200+330 = 3020 potency

So you missed your HT. Big whoop. Do it again. If a DRG misses a positional, they lose potency. If a MNK misses a positional, they lose potency as well. The only difference is MNK shifts stances. However, a MNK changing stances doesn't mean they finish their "combo" with a high potency or powerful skill, making the basis of that comparison incredibly weak.