It would be really nice if it took a few steps to cancel.
It was annoying in FFXI when I'd be in situations where timing required me to cast a spell as my character was coming to a halt, but the one or two steps my character took after I pushed the hot key prevented me from successfully casting.
It's seems pretty nonsensical to have it disrupt from taking one or two steps and it makes for an especially annoying inconvenience to take into consideration in the midst of a high-stress battle.