Every once in a great while, when trying to draw and shoot a 1911 rapidly, I'll get a less than optimal grip and won't depress the grip safety quite as well as I should. The gun won't fire until I adjust my grip. (Perhaps I should practice more with that gun.) Its a very rare thing, and only happens when I'm really pushing it.
That, to me, is just as much as "safety" issue as being concernd about carrying a gun cocked and locked without a grip safety....
(I'm not saying that grip safeties on 1911s are bad, not safe, etc., only that most designs have their strengths and weaknesses, and something that isn't a "weakness" for one shooter might be, for another.)