Stop Cast

[Lyrica_Ashtine]

It allows you to quickly start casting another ability without waiting for a prior cast to finish. Example: I'm casting Stone II on my white mage. Suddenly, the tank gets hit with a big attack because he didn't dodge far enough. I could stopcast the Stone II and start casting a Cure II on the tank, getting the healing spell to the tank around two seconds faster.

You're using the wrong comparison, though. Healers switch from one priority to another: From maiming to mending. In case of Bards and Machinists, they don't switch at all. They just create an unnecessary pause between their attacks to cancel their attack in favor for another.

Not to sound like a broke record, but since I keep getting the same replies, look at how things worked in 2.3 or earlier WoW.

Have you read my previous post about this?