Samurai Tank...

[Jonnycbad]

Tnak makes sense a DPS or a tank. On one hand I can't picture SAM being in heavy tank armor, they'd fit DRG's maiming armor better. But also, I can't picture SAM having positionals from flank/rear as anything other than a frontal fair-and-square attack violates the code of bushido and is seen as dishonorable. NINs are assassins so they get positionals, DRG are pikeman/spearmen are are used to fighting dragons whom are naturally stronger than any man anyway and thus positionals are meant for getting around weakpoints in their hide. MNK is about exploiting weakpoints and feinting/countering (lore-wise, hence Haymaker) so they get positionals for their martial arts. SAM as a DPS would need some kind of good reason to attack from an enemy's blindside. This was alluded to even in FFXI with the Overwhelm trait (which in JP translated to Fair-and-Square) https://www.bg-wiki.com/bg/Overwhelm

[Shippuu]

On one hand I can't picture SAM being in heavy tank armor, they'd fit DRG's maiming armor better.

Your argument falls apart because 90% of Heavensward Dragoon gear is exactly the same as the Fending gear from a visual standpoint. And some sets they have unique looks for are just as heavy or heavier than the equivalent tank gear. So you can't say they couldn't wear the heavy tanking armor and then in the same breath say the Maiming gear would be perfect for them because visually they're the same.