Damage / Buff calculations based on animation is problematic.

[Gilthas]

Instead of the true "instant" description, the interrupt is actually scaled on the duration of the animation.

The description actually says that the "cast time" is instant, which it is.

SE could change all these abilities to be actually instant (Aero surely feels like it hits instantly if I'm not mistaken), but its also true that the playerbase could just accept how these abilities work in the game instead of demanding that they be changed.

I also disagree with saying that the current system is "unresponsive". Unresponsive would be you using an ability and it only starting a few seconds later.