The feathers are definitely working as intended.

There are two main features of stacking resource mechanics like feathers: 1) A means to pool your resources to expend them when you want 2) To prevent over-capping uses of the action in the event you can't use it.

Since the only way to earn stacks is to press a GCD, the second one doesn't apply to Dancer but the first reason fits the design concept and directly mirrors the other aspect of Dancer which is Sabre Dance since, ideally, you also want to pool your Esprit for a phase like Tech Step while also leaving wiggle room (3/4 stacks vs 80/100 Esprit). Having two job features pretty much designed in the same way tells me that it's working as intended.

It sounds like you just don't like the randomness of the job's mechanics which is a valid opinion to have about the feel of the job but I disagree with your assertion that it's not working as intended.