My opinion on positionals is that I think they can be an interesting design element when used thoughtfully, but unfortunately they've been ham-fisted into every single melee class as a careless afterthought. That is, with one exception: Monk is doing it right, with positionals being one of the biggest mechanics for the class. Because they're ominipresent, they give the class a distinct feel to play, that of a close-range fighter that is constantly strategically repositioning.
But all the other jobs suffer from that ham-fisting. For example, when I think of the job fantasy of playing a Dragoon, it's all about doing big jumps and attacking from above. Doing a slight step to the side so that I can attack from the side instead of the back? That doesn't have anything to do with the Dragoon class fantasy. When was the last time you saw Estinien do anything close to that?
And then there's Samurai, a class that very explicitly draws from the romanticized version of everyone's favorite bushido-following warriors. And yet, in opposition to the samurai narrative that the game seems to draw from in every other way, the design of the gameplay explicitly asks Samurai to attack their targets from behind. In the mythos of the Samurai, that's dishonorable...
And of course, then we have Rogue/Ninja. I love when the Rogue backstabs for high damage; it's such an iconic and fun maneuver...but it's mysteriously absent from FF14. There's no attack that makes the big numbers happen when done from behind. Instead, Rogue/Ninja has Trick Attack (which gets a forgettable increase of 100 potency when done from behind) and its other positionals are just the same as the other melee classes. And because every other class has those same positionals, the positionals that Rogue does have in their combos don't feel like a Rogue thing and instead just feel like a melee thing.
To be clear, I'm not opposed to there being technically challenging or engaging elements to playing melee classes, but this ain't it. Melee classes deserve better than to all have positionals crammed into their move lists just because the devs couldn't think of any additional ways to raise the skill ceiling for melee classes that were actually relevant to their job fantasies.