Only if they decide to listen to you, which they explicitly don't have to. And it's especially bad for stuff like control or change, because it could easily turn from "mind control all those soldiers to not attack me" to "mind control the captain of the soldiers to say that I murdered his sister".
Right. Given proper parameters, it would be feasible (and possibly quite cool) to play a caster that routinely casts spontaneously. But given that the results are left to the other players (some who might even be directly/indirectly involved in the same scene), and given that the majority of us are inclined to get a hearty guffaw out of the comical misadventures of others (hello, OT?), I'm inclined to avoid it for the most part.
So far, I'm treating it like the "ooh, let's see what this button does" feature but wouldn't rely on it for anything important.
