Could be wrong as my knowledge on it is limited but the reason it's not based off animations is because of the connection between server to your computer. There's a lag. You can make it better, they can make it better, but we're not at the point of eliminating it. When Titan came out in 2.0 for some people the trial was literally impossible because dodging the slope and puddles being seemingly undoable for the player. Old, old example but Absolute Virtue was literally impossible in FFXI to clear because the seconds needed to react to it's mechanics with abilities were impossible to react to because of a similar delay. So yes, it's THAT hard to program if I'm correct on this.

In short, may not like it but learn to read the cast bar or predict when it's about to happen with experience. You're not going to live long depending on the animations.